Media playback is unsupported on your device Media caption Paul Adams explains the challenges of removing Syria's chemical weapons 
 
 Two Syrian rebel groups in the town of Azaz have agreed a ceasefire. 
 
 The Islamic State in Iraq and Syria (Isis), linked to al-Qaeda, seized the northern town on Wednesday from the larger Western-backed Free Syrian Army. 
 
 Fighting between rebel groups has raised fears of a war within a war. 
 
 The clashes come ahead of a deadline, on Saturday, for Syria to provide a list of its chemical weapons facilities as part of a US-Russian deal for the country to destroy its deadly arsenal. 
 
 Syria's chemical weapons CIA believes Syria's arsenal can be "delivered by aircraft, ballistic missile, and artillery rockets" 
 
 Syria believed to possess mustard gas, sarin, and tried to develop VX gas 
 
 Syria has agreed to join Chemical Weapons Convention; it signed Biological and Toxin Weapons Convention in 1972 but never ratified Sources: CSIS, RUSI UN findings analysed Western military options Chemical weapons allegations 
 
 Russia's Deputy Foreign Minister, Sergei Ryabkov, is currently holding talks in Damascus about the deal. 
 
 But the agreement still faces many hurdles - including the differing opinions of the US and Russia. 
 
 US Secretary of State John Kerry said a "definitive" UN report had proved that the Syrian government was behind a deadly chemical weapons attack in the Damascus suburbs of Ghouta on 21 August. 
 
 But Damascus - backed by Moscow - insists that rebel forces carried out the attack. 
 
 The West also wants any UN resolution on Syria's chemical weapons to include the threat of military force in the result of non-compliance - but Russia objects to any mention of this. 
 
 Syria's President Bashar al-Assad, in an interview with Fox News, said it could take about a year to destroy Syria's chemical stockpiles and could cost about $1bn (£623m). 
 
 Impact unclear 
 
 Analysis What threatened to be an all-out conflict between jihadis linked to al-Qaeda and other rebels in the Free Syrian Army has now been averted - for the time being anyway. But it is unclear what effect this ceasefire will have on the wider situation. There have been clashes between FSA brigades and groups linked to al-Qaeda elsewhere in northern Syria - Azaz is just one small, though important, town. What does this ceasefire mean for the armed uprising? In the short term, if the rebels are fighting each other, they are not fighting the regime. But in the long term, the US and other Western governments might be more willing to support the FSA if they see real distance between it and the jihadis. Clash exposes Syria rebel rifts 
 
 The BBC's Paul Wood, on the Syrian border with Turkey, says that under the ceasefire deal in Azaz the two rebel sides have agreed to exchange prisoners and hand back property. 
 
 It is unclear whether the ceasefire will have an impact on clashes between the groups elsewhere in the country, he says. 
 
 Analysts say there is more chance that the US and other Western powers may arm the Free Syrian Army if it shows a distinct separation from the Islamists. 
 
 The fighting in Azaz began when a wounded rebel - either from Isis or from an allied group, al-Muhajireen - was taken to a field clinic and, while there, he was filmed as part of a fundraising exercise. 
 
 The wounded fighter demanded the film, and called some of his friends to come and help him. 
 
 Free Syrian Army (FSA) rebels from a unit called the Northern Storm brigade were guarding the field clinic, and there was a confrontation which ended up with Isis launching a full attack on the town, pushing out the Northern Storm brigade. 
 
 Isis is reported to have made a number of arrests of activists, journalists and even Sharia court officials during the time it controlled Azaz. 
 
 One eyewitness inside the town said no-one was smoking on the streets - tobacco is forbidden according to strict Islamist doctrine. 
 
 While the Azaz violence seems to have been the result of a particular set of circumstances rather than a long-planned offensive, our correspondent says there is a record of skirmishes between the Jihadis and FSA brigades for control of the border crossings into Turkey. 
 
 Syrian stalemate? 
 
 Meanwhile, the party of Syria's Deputy Prime Minister Qadri Jamil insists he was misquoted in Friday's edition of the UK's Guardian newspaper. 
 
 Mr Jamil reportedly told the paper that the civil war had reached stalemate, with neither government forces nor the rebels strong enough to win - and that the government would use proposed talks in Geneva to call for a ceasefire. 
 
 But the People's Will Party said the Guardian journalist was ''neither precise nor professional'' about what he quoted Mr Jamil as saying. 
 
 Media playback is unsupported on your device Media caption Behind the scenes in a chemical testing lab 
 
 Iranian President Hassan Rouhani has said Tehran is ready to help broker peace in Syria, as part of what he called his country's "constructive engagement" policy with other nations. 
 
 In an article in the Washington Post newspaper, Mr Rouhani wrote: "We must create an atmosphere where peoples of the region can decide their own fates." 
 
 Correspondents say the article is the latest signal that Mr Rouhani wants to improve Iran's relationship with the US and other countries that believe Iran is developing nuclear weapons. ||||| Exclusive: Deputy PM says neither side is strong enough to win and government may call for ceasefire at Geneva talks 
 
 The Syrian conflict has reached a stalemate and President Bashar al-Assad's government will call for a ceasefire at a long-delayed conference in Geneva on the state's future, the country's deputy prime minister has said in an interview with the Guardian. 
 
 Qadri Jamil said that neither side was strong enough to win the conflict, which has lasted two years and caused the death of more than 100,000 people. Jamil, who is in charge of country's finances, also said that the Syrian economy had suffered catastrophic losses. 
 
 "Neither the armed opposition nor the regime is capable of defeating the other side," he said. "This zero balance of forces will not change for a while." 
 
 Meanwhile, he said, the Syrian economy had lost about $100bn (£62bn), equivalent to two years of normal production, during the war. 
 
 If accepted by the armed opposition, a ceasefire would have to be kept "under international observation", which could be provided by monitors or UN peace-keepers – as long as they came from neutral or friendly countries, he said. 
 
 Leaders of Syria's armed opposition have repeatedly refused to go to what is called Geneva Two unless Assad first resigns. An earlier conference on Syria at Geneva lasted for just one day in June last year and no Syrians attended. 
 
 Jamil's comments are the first indication of the proposals that Syria will bring to the table at the summit, which Russia and the US have been trying to convene for months. 
 
 Asked what proposals his government would make at Geneva, he said: "An end to external intervention, a ceasefire and the launching of a peaceful political process in a way that the Syrian people can enjoy self-determination without outside intervention and in a democratic way." 
 
 Although both Moscow and the Obama administration seem committed to convening Geneva Two, a major split has emerged between Russia and the US over who should take part. The US has been urging the Syrian National Coalition, the western-backed rebel group, to drop its boycott but wants the SNC to be the only opposition delegation. 
 
 "The paradox now is that the US is trying to give the SNC the leading role. We're fed up with this monopolistic view," Jamil said. 
 
 Jamil is one of two cabinet ministers from small secular parties who were appointed last year to end the monopoly of the Ba'ath party. 
 
 By joining the government, he said, "we wanted to give a lesson to both sides to prepare for a government of national unity and break the unilateral aspect of the regime – and break the fear in opposition circles about sitting in front of the regime". 
 
 Jamil's comments on why he joined the cabinet were those of his party, but his other comments in the hour-long interview represented the government's position, he said. 
 
 He repeatedly stressed Syria was changing but it needed support rather than pressure. "Let nobody have any fear that the regime in its present form will continue. For all practical purposes the regime in its previous form has ended. In order to realise our progressive reforms we need the west and all those who are involved in Syria to get off our shoulders," he said. 
 
 Jamil said that last week's UN report on the 21 August chemical weapons attack which killed more than 1,000 people was "not thoroughly objective". 
 
 He said Russia had produced evidence showing the rockets that were identified by the UN inspectors as carrying sarin were indeed Soviet-made. But he said they had been exported from Russia to Libya in the 1970s. 
 
 "They were loaded with chemicals by Gaddafi and exported to fundamentalists in Syria after Gaddafi fell," he said. 
 
 On Friday Vladimir Putin said he could not be sure that Assad would fulfil the US-Russian plan to identify and destroy his chemical weapons stocks, but "all the signs" suggested the Syrian regime was serious. 
 
 "Will we be able to accomplish it all? I cannot be 100% sure about it," said Putin, speaking at a discussion forum with western politicians and Russia experts in the north-west of the country. "But everything we have seen so far in recent days gives us confidence that this will happen … I hope so." 
 
 Details of Russia's position on who should represent the opposition at Geneva Two have also emerged. Members of the National Co-ordination Body for Democratic Change in Syria, an umbrella group for several internal parties, met Sergei Ryabkov, a Russian deputy foreign minister, in Damascus on Thursday evening. 
 
 Safwan Akkash, an NCB leader, told the Guardian afterwards that Ryabkov told them Russia was proposing there should be three opposition teams at Geneva. These should be the NCB, the Syrian National Coalition, and a combined delegation of Kurds. 
 
 The SNC, while cautiously accepting Geneva Two as a means of breaking an entrenched stalemate, insists that Assad's resignation remains non-negotiable. 
 
 It is also sticking to a position that a transitional government must follow the ousting of Assad. 
 
 It has remained insistent that those who carried out the chemical attack must be held to account – a point it has hammered home ever since the Russian-US deal to force Syria to hand over its chemical weapons stockpiles. 
 
 • This article was amended overnight on 19-20 September 2013. It originally attributed the use of the term 'civil war' to Qadri Jamil. He did not use this term during the interview. This has been corrected.
– The fighting between al-Qaeda militants and Syrian rebels, which "has raised fears of a war within a war," may now be over, at least in one town, the BBC reports. After seizing the town of Azaz this week, the al-Qaeda-linked Islamic State in Iraq and Syria (ISIS) agreed to a ceasefire with the Free Syrian Army's area forces, and both sides have exchanged prisoners and returned property. The deal was arranged by a rebel brigade with ties to the FSA, AFP reports, though it's not clear if the truce will extend beyond Azaz to end infighting elsewhere between Assad's enemies. Analysts say a distinct separation from the jihadists may boost the chances of the US or other Western countries arming the FSA, whose members ISIS has accused of being "heretics" cooperating with the West. But this ceasefire may not be the only one in Syria shortly. "Neither the armed opposition nor the regime is capable of defeating the other side," Syria's deputy prime minister tells the Guardian. "This zero balance of forces will not change for a while," he adds, claiming Assad's government will call for "an end to external intervention, a ceasefire, and the launching of a peaceful political process" during the proposed Geneva talks.