(CNN) Two guinea pigs and a cat belonging to former Russian spy Sergei Skripal, poisoned in a nerve agent attack in the UK last month, have died, British authorities have said. 
 
 The two guinea pigs were found dead in Skripal's house some time after the attack, apparently from dehydration, and a cat was put down after being discovered in a "distressed" state. Police sealed the house after Skripal and his daughter Yulia were discovered unconscious on a bench in Salisbury on March 4. 
 
 "When a vet was able to access the property, two guinea pigs had sadly died," the UK Department for Environment, Food and Rural Affairs (DEFRA) said in a statement. "A cat was also found in a distressed state and a decision was taken by a veterinary surgeon to euthanise the animal to alleviate its suffering." 
 
 The guinea pigs "most likely... died due to a lack of water," a DEFRA spokesperosn told CNN later. 
 
 The deaths are the latest peculiar developments in a story that has taken a turn for the absurd in recent days. Apparently in an effort to shift the debate away from the issue of culpability, a succession of Russian officials have attempted to make light of the whole affair. ||||| Ex-spy’s improving condition raises prospect he will be able to give vital clues to poison attack 
 
 Sergei Skripal and his daughter, Yulia, have become caught up at the centre of an international tussle between the UK and Russia following an announcement by doctors that the former Russian spy was getting better and was “no longer in a critical condition”. 
 
 
 
 One month after the pair were found collapsed on a park bench in Salisbury in Wiltshire, having been poisoned with a deadly nerve agent, the hospital treating them said on Friday that they were both recovering. 
 
 Amid reports that Viktoria Skripal, Sergei Skripal’s niece, had been denied a visa to visit the UK, news of the improvement in his condition raises the prospect that he will be able to give police vital clues as to who might have poisoned him and why. 
 
 The testimony of the Skripals would be crucial in establishing the credibility of the government’s claim that it was “highly likely” the Russian state targeted them with the nerve agent novichok. Moscow has waged a furious media battle in an attempt to discredit this account and will probably want to bring Yulia Skripal back to Russia. 
 
 Play Video 0:59 Sergei Skripal responding well to treatment, says Salisbury hospital – video 
 
 Dr Christine Blanshard, the medical director at Salisbury district hospital, revealed the Skripals’ improving condition on Friday afternoon. 
 
 In a statement that she said was made in response to intense media coverage, Blanshard said Yulia Skripal’s strength was improving daily and she would be leaving hospital soon. 
 
 
 
 She added: “I also want to update you on the condition of her father, Sergei Skripal. He is responding well to treatment, improving rapidly and is no longer in a critical condition.” 
 
 A Foreign Office spokesman said the government was pleased that the Skripals were in better health but added: “Let us be clear, this was attempted murder using an illegal chemical weapon that we know Russia possesses.” 
 
 The Russian embassy to the UK tweeted: “Good news!” 
 
 According to the BBC, the government has refused to give a visa to Viktoria Skripal, who has made repeated appearances on Russian state TV in recent days and has sought to travel to Britain. She has suggested that her relatives may have been the victims of food poisoning. 
 
 
 
 “It appears the Russian state is trying to use Victoria as a pawn,” a government source told the BBC, adding: “If she is being influenced or coerced by the Kremlin, she has become another victim.” 
 
 In a telephone conversation apparently recorded by Viktoria Skripal in Moscow on Thursday, Yulia Skripal was asked about her father’s condition. She said: “Everything’s OK, he’s resting now, he’s sleeping. Everyone’s health is OK. No one has had any irreversible [harm].” She appeared to decline her cousin’s offer of a visit. 
 
 
 
 It is unclear if detectives have yet had the opportunity to interview Sergei Skripal about events leading up to his poisoning. On Thursday, his daughter released a statement through the Metropolitan police in which she said she was getting stronger by the day. 
 
 Russian diplomats have been insisting they gain access to Yulia Skripal, who is a Russian citizen. Her father has a British passport following his arrival in the UK in 2010, as part of a spy swap. On Thursday, Yulia Skripal described waking up to find herself at the centre of a global incident as “extremely disorientating”. 
 
 The Kremlin’s strategy has been to exploit weaknesses and inconsistencies in the UK’s case. It seized on a blunder by the foreign secretary, Boris Johnson, who claimed, wrongly, that the government science facility at Porton Down had attributed the nerve agent to Russia. In fact, the attribution was based on intelligence and analysis of previous Russian state hits. 
 
 
 
 Facebook Twitter Pinterest Sergei Lavrov, Russia’s foreign minister, accused the UK government of engaging in “frantic and convulsive efforts to find arguments to support their indefensible position”. Photograph: Alexander Shcherbak/TASS 
 
 On Friday, Russia’s foreign ministry opened a new and surreal front in its information war. Sergei Skripal’s two guinea pigs died after the nerve agent attack from dehydration after his home was sealed off, the UK government said. The ex-spy’s cat was found in a “distressed” state and had to be put down. 
 
 “What happened to these animals? Why doesn’t anyone mention them? Their condition is also an important piece of evidence,” the foreign ministry spokeswoman Maria Zakharova wrote on Facebook, adding: “The more we know, the worse the picture looks.” 
 
 The Russian foreign minister, Sergei Lavrov, accused the UK government of engaging in “frantic and convulsive efforts to find arguments to support their indefensible position” instead of producing evidence. Lavrov’s comments echoed those of Russia’s ambassador to the UN, Vassily Nebenzia, who on Thursday likened the UK’s claims to Alice and Wonderland and the TV series Midsomer Murders. 
 
 The Skripal case bears comparison with the 2006 murder of Alexander Litvinenko, who was killed by two Russian spy agency assassins with a radioactive cup of tea. Before he died, Litvinenko had given nine hours of evidence to detectives. This proved invaluable to Scotland Yard’s investigation and shaped a public inquiry, which ruled that the Russian president, Vladimir Putin, “probably approved” the operation. 
 
 Litvinenko’s father, Walter, blamed Putin for his son’s death. After living in exile in Italy, where he was broke and unhappy, he returned in 2012 to Russia, seemingly having struck a deal with the state. 
 
 Last week, he appeared on Russian TV talk shows. He blamed the CIA for his son’s death and even shared a sofa with the alleged killer Andrei Lugovoi, a deputy in Russia’s Duma, who has been commenting on the Skripal case. At one point, Walter Litvinenko clasped Lugovoi warmly by the hand. 
 
 The international alliance that has expelled 342 diplomats in solidarity with Britain is holding firm. The UK’s stand against Moscow was boosted on Friday when members of the US Congress introduced a legislative initiative to target Russian financial institutions and to reinforce US support for the UK government. 
 
 
 
 Mike Turner, a Republican, and Joaquin Castro, a Democrat, said that they were introducing the bipartisan stand with UK against Russia violations bill in response to the attack on the Skripals. 
 
 “The Russian government-sanctioned attack on Sergei and Yulia Skripal and Officer Nick Bailey last month on British soil violated international law and indicates Putin’s growing aggression and disregard for international standards of conduct,” said the two members of the House intelligence committee. 
 
 
 
 What will happen now Sergei Skripal is no longer critically ill? Read more 
 
 “It’s imperative that the United States stands with the United Kingdom and our international partners in signalling resolve with a strong response.” 
 
 They said the bill would target Russian financial institutions until Russia ceased the practice of assassinating expatriates and dissidents outside of Russia. 
 
 Meanwhile, British and American authorities have been given several chemical analyses of a substance believed to be the nerve agent novichok produced in Russia’s closed Shikhany military facility. 
 
 Boris Kuznetsov, a lawyer who fled Russia in 2007, said he had handed British diplomats the police case files from the 1995 murder of a Russian banker and his secretary with a toxic substance. Scientists have identified it as a product of the Soviet-designed Foliant programme. 
 
 Among the documents are the results of a mass spectrometry and an infrared spectroscopy of the poisonous substance. It was scraped off a telephone receiver used by the businessman Ivan Kivelidi and his secretary. Both died in agony. ||||| Image caption Sergei Skripal, 66, and his daughter Yulia, 33, remain in hospital 
 
 Russian former spy Sergei Skripal is no longer in a critical condition after being poisoned by a nerve agent, doctors have said. 
 
 Salisbury District Hospital said Mr Skripal is responding well to treatment and "improving rapidly". 
 
 Mr Skripal, 66, and his daughter Yulia, 33, have been in hospital for more than a month after being found unconscious on a bench in Salisbury. 
 
 They had been poisoned with a toxic nerve agent called Novichok. 
 
 Ms Skripal is conscious and talking in hospital. 
 
 The UK government claims Russia is behind the attack but Moscow has denied all involvement, calling the accusations "horrific and unsubstantiated". 
 
 Meanwhile, the UK has refused to grant a visa to Yulia's cousin, Viktoria Skripal, the BBC has learned. 
 
 The Home Office said the application did not comply with immigration rules. A government source told the BBC it appears Russia is "trying to use Viktoria as a pawn". 
 
 The Russian Embassy said Sergei and Yulia Skripal "remain hidden from the public" as a result of the visa decision and the "only relative" who could reasonably expect to see them is "kept out of the UK". 
 
 "The stubborn refusal to cooperate, to provide transparency and to answer the numerous questions means Britain has something to hide," an embassy spokesman said. 
 
 Viktoria later told the BBC she did not have enough money in her bank account to satisfy the visa requirements. 
 
 It comes after Russian TV aired a recording of an alleged phone conversation between Viktoria and Yulia on Thursday. 
 
 Doubts were raised over its authenticity but Viktoria has told Newsnight she was 100% certain it was Yulia. 
 
 'Strength is growing' 
 
 In a statement from the hospital, medical director Christine Blanshard urged people to respect Ms Skripal's privacy "while she continues to get better". 
 
 "As Yulia herself says, her strength is growing daily and she can look forward to the day when she is well enough to leave the hospital," Dr Blanshard said. 
 
 "Any speculation on when that date will be is just that - speculation." 
 
 Image copyright BBC Russian Image caption Viktoria Skripal gave the BBC this picture of Sergei Skripal (centre) with his daughter Yulia and late son Alexander 
 
 The BBC's diplomatic correspondent James Landale said Mr Skripal's recovery meant "we now have two individuals at the heart of this incident in Salisbury who can now speak". 
 
 He said: "They can speak to investigators about their last movements, were there any threats, were there any other circumstances?" 
 
 Following the update on Mr Skripal's condition, the Russian Embassy tweeted: "Good news!" 
 
 The embassy later issued a statement wishing the Skripals "get well soon" and expressed hope that their recovery will "contribute to the investigation". 
 
 "We are confident that the objective probe will ultimately establish that the claims against Russia by [the] UK government are null and void," it added. 
 
 Foreign Secretary Boris Johnson also called Mr Skripal's condition "great news" and a testament to the emergency services and NHS staff. 
 
 The Foreign and Commonwealth Office said it was "very pleased" that the Skripals were improving. 
 
 "The NHS will continue to provide ongoing care for the Skripals, both of whom are likely to have ongoing medical needs," the FCO said. 
 
 "Let us be clear, this was attempted murder using an illegal chemical weapon that we know Russia possesses." 
 
 Analysis: Long-term recovery 
 
 By BBC Health and Science Correspondent James Gallagher 
 
 Recovery from a nerve agent attack is not guaranteed, but it is not always a surprise either. 
 
 Nerve agents including sarin, VX and novichok all prevent nerves functioning normally. This includes those that are necessary to breathe and keep the heart beating. 
 
 They work by disrupting an enzyme called acetylcholinesterase at the junction between nerves. 
 
 But over time, the nerve agent is metabolised and excreted by the body and new acetylcholinesterase is made. The question is whether doctors can keep patients alive long enough for that to happen. 
 
 This would have been the focus of Sergei and Yulia Skripal's care at Salisbury District Hospital. It could have included heart and lung support, the drug atropine to counteract the effect of nerve agents and sedation to prevent brain seizures. 
 
 There is still a question about the Skripals' long term recovery and whether there will be any impact on memory and brain function. 
 
 Former double agent Mr Skripal, who was jailed by Russia for spying for Britain's intelligence service but released as part of a spy swap between the US and Russia in 2010, was being visited by his daughter Yulia when the attack happened on 4 March. 
 
 The pair became ill in the centre of Salisbury after visiting The Mill pub and Zizzi restaurant. 
 
 The incident sparked an escalating diplomatic crisis between Russia and the West, with more than 20 countries expelling Russian envoys in solidarity with the UK. 
 
 Image copyright AFP/Getty Images Image caption Emergency service workers in biohazard suits fix a tent over the bench where pair were found 
 
 On Thursday, Russia's ambassador to the UN, Vasily Nebenzia, told the UN Security Council that Britain was "playing with fire" and had invented a "fake story". 
 
 Mr Nebenzia said Britain's main goal had been "to discredit and even delegitimise" Russia and accused the government of waging a "propaganda war". 
 
 'Respect my privacy' 
 
 In a statement released to police on Thursday, Ms Skripal said she was grateful for the many messages of goodwill she had received and the people of Salisbury who came to her aid. 
 
 She said: "I am sure you appreciate that the entire episode is somewhat disorientating, and I hope that you'll respect my privacy and that of my family during the period of my convalescence." 
 
 Britain's UN ambassador, Karen Pierce, said Russia's request for consular access to Ms Skripal has been passed on. ||||| New York (CNN) Russia, at a United Nations Security Council meeting, warned the British government Thursday it was "playing with fire" with accusations that Moscow was behind the poisoning of a Russian former spy and his daughter in the United Kingdom. 
 
 Russia's UN Ambassador Vassily Nebenzia blasted the UK, calling the allegations against Russia a "fake story." 
 
 The Russian UN diplomat warned "we have told our British colleagues that they are playing with fire and they will be sorry." 
 
 Asked after the meeting what he meant by saying the UK would be sorry, Nebenzi replied that if the UK's accusation was untrue, "a normal person should be sorry for that." 
 
 He accused the United Kingdom of turning other countries against Russia. 
 
 "You started a wave that even reached New York," he said. 
 
 Moscow, emboldened after the UK was forced to withdraw a claim that its scientists had pinned the blame on Russia for the attack, further attempted to embarrass Britain in front of its international allies. 
 
 But the UN ambassador from the UK, Karen Pierce, said she would not be lectured by Russia, which she said had blocked inquiries into the use of chemical weapons in Syria. 
 
 "Everything we have done ... has been consistent with the Convention on Chemical Weapons," she said. 
 
 Russia refused to help when the UK asked early in the investigation, Pierce said. 
 
 Pierce told the Council "we all know why that investigation is underway. It's because a military-grade nerve agent was used in an attempt to kill civilians on British soil. It was carried out recklessly and it was carried out without regard for public safety." 
 
 She questioned the need for Thursday's meeting, saying the chemical weapons watchdog, the Organization for the Prohibition of Chemical Weapons, has yet to release its report on the incident. 
 
 Battle of barbs continues 
 
 A month after former Russian double agent Sergei Skripal and his daughter Yulia were poisoned in the English city of Salisbury, the United Kingdom and Russia remain locked in a battle over who is to blame. 
 
 UK Prime Minister Theresa May has said it was "highly likely" the attack was ordered by the Russian government. The Kremlin has repeatedly denied the accusation. Russian Foreign Minister Sergey Lavrov said Thursday that the affair was a "pretext" for the expulsion of Russian diplomats around the world. 
 
 On Wednesday, Moscow failed in its efforts to persuade OPCW to allow a joint UK-Russia investigation into the attack. The OPCW is already carrying out an independent investigation at the UK's request, and expects to receive the results of its analysis within a week. Britain is also carrying out its own inquiry, with support from the OPCW. 
 
 Attention has turned to the United Nations. It was the second time the Security Council discussed the poisoning. At a March 15 meeting that was called by the UK, US Ambassador to the United Nations Nikki Haley blasted the Russian government for the attack and called for a firm international response. 
 
 Skripal, 66, and his daughter Yulia, 33, remain in Salisbury District Hospital following the attack on March 4. Sergei Skripal is described as in a critical but stable condition. 
 
 Yulia Skripal announced Thursday that she had woken up "over a week ago" and that her "strength is growing daily." 
 
 "I am grateful for the interest in me and for the many messages of goodwill that I have received," Skripal said in a statement released on her behalf by London's Metropolitan Police. 
 
 "I have many people to thank for my recovery and would especially like to mention the people of Salisbury that came to my aid when my father and I were incapacitated. Further than that, I would like to thank the staff at Salisbury District Hospital for their care and professionalism," she said. 
 
 "I am sure you appreciate that the entire episode is somewhat disorientating, and I hope that you'll respect my privacy and that of my family during the period of my convalescence," she added. 
 
 Pierce said the UK has relayed a request for a visit from a Russian consular official to Skripal. 
 
 "We await her response," Pierce said. 
 
 A Russian state television station reported Thursday that Viktoria Skripal, the cousin of Yulia Skripal, said she had spoken to Yulia by phone. 
 
 UK experts believe the Skripals were poisoned with a Russian-made nerve agent, Novichok 
 
 The Times of London, citing unnamed sources, reported on Thursday that UK security services had pinpointed the location of the Russian laboratory that manufactured the nerve agent. 
 
 Putin: Common sense must prevail 
 
 On Wednesday, speaking at a trilateral summit with Turkey and Iran, Russian President Vladimir Putin told reporters he wanted to see "a healthy political process" based on international law. 
 
 "We are not expecting anything but common sense to prevail; international relations will not tolerate the recent damage done," he said. 
 
 The UK expelled 23 Russian diplomats in the wake of the attack, sparking a wave of similar moves by UK allies around the world. The US expelled 60 Russian diplomats as part of the international effort. Moscow responded by kicking out diplomats from at least 23 countries , including 60 American diplomats. It also ordered the closure of the US consulate in St. Petersburg. 
 
 Lavrov said Thursday that Russia wants "to find the truth" about the poisoning in Salisbury and that "provocations are being arranged" in the Skripal case to demonize Russia. 
 
 He claimed that many countries had been pressured into supporting the UK and described the mass expulsion of Russian diplomats as "an open mocking of diplomatic ethics" that had not seen for a long time. 
 
 Russian Ambassador to the United Kingdom Alexander Yakovenko told a news conference Thursday that Russia has "no information about Yulia Skripal, we don't know about Sergei." 
 
 Speaking to reporters at the Russian Embassy in London, Yakovenko said Yulia's cousin Viktoria was "waiting for the visa in Moscow, a British visa. We will see what will be the outcome of that visit." 
 
 He repeated Russia's complaint that Britain is not allowing it access to its citizens, Sergei and Yulia Skripal, or to the British investigation into their poisoning. The UK government must be "transparent" about the evidence, he said. 
 
 Yakovenko said Russia would accept the result of the OPCW investigation -- but suggested that its validity would depend on which nations' experts were involved. "These results should be confirmed by the international community, so we want to see who are the experts," he said. 
 
 Questions around nerve agent's source 
 
 Questions continue to dog the investigation into the attack on the Skripals, who were found slumped on a bench at an outdoor shopping complex in Salisbury. UK police believe they came into contact with the military-grade nerve agent on Skripal's front door. 
 
 On Tuesday, UK scientists said that while they had identified the nerve agent as Novichok, they were unable to say exactly where it had been manufactured. 
 
 "We have not identified the precise source, but we have provided the scientific info to government, who have then used a number of other sources to piece together the conclusions you have come to," Gary Aitkenhead, chief executive of the UK government laboratory at Porton Down, told Sky News on Tuesday. 
 
 Further complicating the picture, the UK Foreign Office confirmed on Wednesday it had deleted a tweet that claimed that British chemical weapons experts believed Russia had produced the nerve agent. The Foreign Office said the tweet was "truncated and did not accurately report" a briefing by the British ambassador to Moscow last month. 
 
 The British government says the scientific analysis from Porton Down forms only part of the picture. It insists that only Russia had the capability to carry out the attack, that Moscow had identified former double agents as legitimate targets, and was known for its involvement in state-sponsored attacks in the past. 
 
 In its report on Thursday, the Times of London cited security sources claiming that the location for the manufacture of the Novichok had been identified "using scientific analysis and intelligence in the days after the attempted murder of Sergei and Yulia Skripal a month ago." 
 
 The Times said security sources didn't have "100% certainty" but there was a high degree of confidence in the location. The UK government had known about the facility's existence before the attack on March 4, it added. 
 
 The UK Foreign Office refused to comment on The Times' report. "We have nothing more to add to that story," a spokesman told CNN.
– First good news on Yulia Skripal; now an optimistic outlook for her dad. Doctors at the UK hospital where Sergei Skripal has been convalescing since his March 4 poisoning report the 66-year-old ex-Russian spy is "responding well to treatment, improving rapidly, and is no longer in a critical condition," per Christine Blanshard, the medical director at Salisbury District Hospital. Skripal is said to be "conscious and talking," per the BBC. The Guardian reports that Blanshard also confirmed Yulia Skripal's improving health, noting Yulia "can look forward to the day when she is well enough to leave the hospital." In one sad development, however, CNN does report three deaths: that of Skripal's two guinea pigs, which British authorities say apparently died of dehydration, and his cat, which had to be euthanized after being found in a "distressed state." The animals were found "some time after the attack," and some are wondering why it took so long to find them—including the Russian Embassy in London. "Are they seriously saying that nobody had a look at the pets at alleged crime scene?," the embassy tweeted Friday. "Were the animals' remains tested for toxic substances? Or just disposed of as an inconvenient piece of evidence?" At a UN Security Council meeting Thursday, Russia's UN ambassador accused the UK of "playing with fire" in accusing Russia of being behind the poisonings, per CNN.