Writing exclusively for The Independent, Mr Watson said the stories making allegations about Mr Corbyn‘s contact with a Czech agent in the 1980s are “false and ridiculous smears” based on discredited sources.
The senior Labour figure goes on to accuse the newspapers’ proprietors of abusing their power to print “poorly sourced” stories simply because it suits their political agenda.
He argues the new attacks on Mr Corbyn fit a pattern going back decades, which has also seen the same papers attack Ed Miliband’s father as “the man who hated Britain” and vilified Neil Kinnock.
Mr Watson’s attack comes as Mr Corbyn was forced to threaten legal action against Ben Bradley, an MP and a vice chair of the Conservatives, who, after reading the newspaper coverage, made claims on social media that the Labour leader had “sold British secrets” to communist spies.
In his article, Mr Watson writes: “Newspaper proprietors in this country abuse their power.
“It’s a unique kind of self-harm for a newspaper to print a story they know is poorly sourced, decide to run it regardless because it suits their political agenda, and pass it off as news.
“There are many reasons for declining newspaper circulation, but there can be no doubt the public is beginning to tire of the fact that too many papers routinely present smears, lies and innuendo as facts.”
The controversy first began when The Sun reported on files in Czech archives that appeared to show the current Labour leader had met with a Czechoslovakian agent at least three times in 1986 and 1987.
Mr Corbyn admits to one meeting but insists he thought Jan Sarkocy was a diplomat, and strongly denies giving him any information.
Sarkocy, a former Czech spy who worked for the Statni Bezpecnost (StB) secret police during the Cold War, says he met Mr Corbyn a number of times, including twice in the House of Commons.
The ex-agent, who now lives in the Slovakian capital Bratislava, has also claimed to have personally organised the Live Aid concern in 1985, which he said was “funded by Czechoslovakia”.
Mr Watson wrote: “Documents do not substantiate his wild claims.
“In fact, the director of the Czech security forces archive says that historic records show the opposite to what he claims – that Jeremy Corbyn was not a ‘collaborator’ and that the Czech official he met deliberately concealed his true identity.”
He added: “Unfortunately for these newspapers, the years of slurs, of stretching the truth to breaking point, of completely one-sided reporting may be creeping up on them.
“They do not wield the power they once did, their circulations are falling and people simply don’t trust them anymore.”
Theresa May chose to comment when she was asked about the claims in a press conference yesterday, responding that all MPs need to be “open and transparent” about their dealings in the past.
Conservative Ben Bradley MP took to Twitter to tell another social media user that “Corbyn sold British secrets to communist spies”.
He later deleted the tweet when Mr Corbyn’s office threatened him with legal action unless he removed the allegation.
Mr Corbyn’s spokesman has said of the stories more broadly: “The claim that he was an agent, asset or informer for any intelligence agency is entirely false and a ridiculous smear.
“Like other MPs, Jeremy has met diplomats from many countries. In the 1980s he met a Czech diplomat... Jeremy neither had nor offered any privileged information to this or any other diplomat.”
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