Acclaimed author JK Rowling has mocked Donald Trump for his Twitter posts, likening the president's way of writing to the speech of a school yard bully. 

Responding to a tweet from the president accusing the New York Times of being “fake news”, the Harry Potter author said Mr Trump's message to that of a boastful child with a poor grasp of the English language, and very few friends. 

“I don’t care what Kids at School call me because they are all Disgusting Fake Losers and my Real Friends go to a different Scool you haven’t heard of and they think Im the Coolest and Smartest and we go to parties and I don’t have to tell you there Names for this to be True,” Rowling wrote in the tweet, purposefully imitating the president’s tendency to capitalise words inappropriately, and his frequent grammatical and spelling errors. 

Mr Trump had tweeted to attack a report the New York Times had written that suggested White House counsel Donald McGahn has been cooperating extensively with special counsel Robert Mueller’s investigation into Russian meddling in the 2016 election and possible collusion with Trump campaign officials. 

In a series of tweets, Mr Trump confirmed that he had authorised Mr McGahn’s cooperation with the investigation — saying he had "nothing to hide” — but suggesting that the article had falsely implied that Mr McGahn had “turned” on him. 

In response to the allegations of fake news coming from Mr Trump, the New York Times released a statement saying that the paper stands behind the story, and the two reporters who wrote it. 

Trump in Helsinki: Putin meeting and protests Show all 16 1 /16 Trump in Helsinki: Putin meeting and protests Trump in Helsinki: Putin meeting and protests President Trump meets with Russian President Vladimir Putin in Helsinki Reuters Trump in Helsinki: Putin meeting and protests An advert from Finnish newspaper Helsingin Sanomat is on display in Helsinki Reuters Trump in Helsinki: Putin meeting and protests President Trump in a meeting with Finnish President Sauli Niinisto AFP/Getty Trump in Helsinki: Putin meeting and protests President Trump meets with Finnish President Sauli Niinisto in Helsinki EPA Trump in Helsinki: Putin meeting and protests President Trump talks with Finnish President Sauli Niinisto in Mantyniemi, the official residence of the Finnish President EPA Trump in Helsinki: Putin meeting and protests US, Finnish and Russian flags fly in front of the Presidential Palace in Helsinki EPA Trump in Helsinki: Putin meeting and protests A protester wears a mask featuring a portrait of Russian President Vladimir Putin during the so-called "Helsinki against Trump and Putin" demonstration on July 16, 2018, in the Finnish capital Helsinki.  The US and Russian leaders opened an historic summit in Helsinki on Monday, with Donald Trump promising an "extraordinary relationship" and Vladimir Putin saying it was high time to thrash out disputes around the world. /  AFP PHOTO / Jonathan NACKSTRANDJONATHAN NACKSTRAND/AFP/Getty Images JONATHAN NACKSTRAND AFP/Getty Trump in Helsinki: Putin meeting and protests Vladimir Putin gifts a football to President Trump at the press conference that followed their meeting AP Trump in Helsinki: Putin meeting and protests Trump supporters hold banners during a demonstration in Helsinki AFP/Getty Trump in Helsinki: Putin meeting and protests People protest for women's reproductive rights in Helsinki's Senate Square Reuters Trump in Helsinki: Putin meeting and protests A crowd watches the motorcade transporting President Trump through Helsinki AFP/Getty Trump in Helsinki: Putin meeting and protests Russian President Putin drives through Helsinki on his way to meet with President Trump EPA Trump in Helsinki: Putin meeting and protests A man in the audience of the joint press conference holds up a sign sign that reads "NUCLEAR WEAPON BAN TREATY".  REUTERS Trump in Helsinki: Putin meeting and protests A man is removed from the joint press conference in Helsinki.  Security removed the man after he pulled out a sign that read "NUCLEAR WEAPON BAN TREATY".  REUTERS Trump in Helsinki: Putin meeting and protests President Trump and Russia's President Putin sit for a working lunch in Finland's Presidential Palace AFP/Getty Trump in Helsinki: Putin meeting and protests President Trump meets with Russian President Vladimir Putin in Helsinki Reuters

Mr Trump has regularly criticised the special counsel’s investigation, saying that the whole affair is a “witch hunt” targeting him and his campaign. 

The investigation has not at this point implicated Mr Trump personally, but has resulted in more than a dozen indictments related to meddling in the 2016 election.  At least five individuals charged by the special counsel’s team have pleaded guilty to charges.