John McDonnell: Media treatment of Corbyn is appalling
The comments come after Mr Corbyn accused the BBC of an "unacceptable breach" of its impartiality rules when shadow minister Steve Doughty resigned on live TV.
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Mr Doughty revealed he was resigning as Shadow Foreign Office minister on Wednesday’s edition of the Daily Politics just minutes before Prime Minister's Questions.
The BBC’s political editor Laura Kuenssberg had agreed with Mr Doughty that he would announce his resignation live on air.
Mr McDonnell said that the programme had “clearly decided to do maximum damage to Jeremy's standing," although he emphasised that his comments were not an attack on the BBC or Ms Kuennsberg.
"There is a private company that makes the politics programme which is commissioned by the BBC," he told politics.co.uk.
A petition to sack Andrew Neil and Laura Kuenssberg after the resignation has garnered nearly 12,000 signatures since it was created.
But Mr Doughty told the Huffington Post any suggestion that he had been coerced to resign by the BBC was “beyond ridiculous”.
“This new complaint suggesting some dark conspiracy theory is not only embarrassing, embarrassing, embarrassing - it is handing fuel to Tory enemies of one our most crucial national institutions that Labour members and voters rightly want us to protect,” he said.
‘OPPOSE AND UNDERMINE’
Mr McDonnell said the newspapers during the leadership election had attempted to “undermine” Mr Corbyn.
"None of them, except the Morning Star, supported us," he said during a speech in Northampton. "Even the liberal left Guardian opposed us and undermined us at every opportunity."
"It can sound like we're paranoid but the reality is that the treatment Jeremy has had across the media has been appalling," he said.
"It's the worst any politician has been treated. The problem with the BBC and other broadcasters is that because of the cut backs that have gone on with journalists, they are taking their stories from newspapers rather than investigating and reporting for themselves and therefore the bias of the press infects the broadcast media too."
But Mr McDonnell said the media coverage did not have a detrimental effect on the Labour leadership.
“It's an object lesson about the establishment using its power in the media to try and destroy an individual and what he stands for," he said.
"It's proved to be counterproductive because the more attacks on Jeremy, the more members we recruit."
He argued the way to challenge the media treatment would be for him and Mr Corbyn to do more live interviews. He said the public were surprised when he did interviews that he did not have “two heads or horns”.
He also dismissed the idea that there is a civil war in the Labour party, saying: "Don't believe everything you read in the Daily Mail.
"There's a small handful of them that can't accept Jeremy's leadership but we will bring them back on board."