Labour launched a “vicious and libellous” smear campaign to “attack and demean” whistleblowers as union chiefs view the party’s anti-Semitism crisis as “designed to bring Jeremy Corbyn down”, a party whistleblower has said. 

Writing exclusively for HuffPost UK in the wake of the shock BBC Panorama investigation, the party’s former head of disputes, Sam Matthews, takes aim at his former union, Unite, and its boss Len McCluskey. 

Matthews, who revealed he contemplated suicide during months spent dealing with anti-Semitism complaints for Labour, said it “should have been a watershed moment for the party” when he and seven others spoke to the BBC investigation.

Instead the party’s press operation “started smearing” whistleblowers “before the programme had even aired”, he said, adding that party chiefs “chose to come after the messengers with a vicious and libellous attack, with no due care to the emotional and mental wellbeing of those involved”. 

His blog is published as the Jewish Leadership Council writes to the shadow cabinet warning them to act on “more denial, more bullying, more falsehoods and more hatred” being pedalled by party members. 

Matthews, who has left Unite to join the GMB union, goes on to accuse McCluskey of failing his union members, many of whom work for the Labour Party. 

He slammed the “closeness of Unite’s general secretary to the Labour Leadership”.

He said Unite members working for Labour fear reprisals and that they are “being abandoned by their union”, adding: “Len McCluskey has described legitimate concerns that the Labour Leadership is not taking action on antisemitism, racism and misogyny as being designed to ‘bring Jeremy Corbyn down’.” 

He said during his time working for the party he felt suicide “was my only option to stop feeling complicit in what I saw going on”.

The launch of the Equality and Human Rights Commission’s investigation into Labour anti-Semitism “represents the most shameful moment in its 119 year history”, he said, adding: “Sadly at least, I am fairly sure, until the findings of their inquiry are released. It is shameful that the Labour Party now stands alongside the BNP in the roll call of political parties investigated by the regulator.” 

Jonathan Goldstein, the chair of the Jewish Leadership Council (JLC), meanwhile has written to shadow ministers in a letter today, ahead of an extraordinary meeting on the crisis next week, and hits out at “social media activists and fake news sites” which are “at a barely deniable arm’s length from the leadership”.

He writes: “To our disgust, when we and others challenge and expose this problem, the reaction is more denial, more bullying, more falsehoods and more hatred against us, our community and those with the integrity to support us.

“Occasionally, the attacks come from in and around the leader’s office, but it is also the constant function of social media activists and fake news sites that incite anger at a barely deniable arm’s length from the party leadership.” 

Goldstein also writes that anti-Semitism is a “a collective culture that attacks female Jewish Labour MPs, the Jewish Labour Movement and anybody deemed ‘Blairite’ or ‘Zionist’.” 

He concludes: “As members of the Shadow Cabinet, you now face a very difficult and unavoidable decision, in which inaction will signal your support for what has happened and what will follow.

“Please, do not under-estimate the importance of your actions for the future well-being of British Jews, or for the wider message that you give about racism, liberal democratic values and our British society.” 

A Labour Party spokesperson said the party “is implacably opposed to anti-Semitism and determined to root it out of our movement and our society”.

They added: “We stand in solidarity with Jewish people and we are fully committed to the support, defence and celebration of the Jewish community and its organisations.

“We are taking decisive action against anti-Semitism, doubling the number of staff dedicated to dealing with complaints and cases, and swiftly suspending and taking robust action against individuals. Since Jennie Formby became general secretary, the rate at which anti-Semitism cases have been dealt with has increased more than four-fold. We will continue to act against this repugnant form of racism.”

HuffPost UK has contacted Unite the union for comment.