Dame Margaret Hodge, a Jewish MP, hit out at the party’s handling of alleged cases of antisemitism saying it had become “secretive and intimidating”.
She criticised leader Jeremy Corbyn and his allies and challenged them to “stop thinking they’ve got everything right and they don’t have to listen to the rest of us”.
Top officials were also urged by shadow foreign secretary Emily Thornberry not to pursue legal action against whistleblowing former Labour staffers, some of whom have broke Non-Disclosure Agreements (NDAs).
A party spokesperson told Sky News it takes all antisemitism complaints “extremely seriously” and was “committed to challenging and campaigning against it in all its forms”.
Dame Margaret told Sky News’ Sophy Ridge on Sunday she would stay in Labour and fight but that there were “many more people who will feel so uncomfortable within the Labour Party that they can no longer remain within”.
She criticised Labour’s response to a Panorama documentary earlier this week, which saw former workers claim they were undermined in their efforts to tackle antisemitism in the party.
It was “utterly deplorable and an abuse of power” for the leadership to “pursue these people with lawyers” to “shut them up”, the Barking and Dagenham MP said.
She also defended deputy leader Tom Watson, who has piled pressure on Labour’s general secretary Jennie Formby to do more to tackle antisemitism and is currently receiving chemotherapy.
Dame Margaret called for people to “leave her to cope with the treatment that she’s undergoing” but added: “You cannot fail to deal with this issue and Tom Watson is absolutely right to be calling this out”.
Ms Thornberry also defended Ms Formby, but cautioned against threatening the whistleblowers.
“We shouldn’t be going for the messengers, we should be listening to the message,” she told the BBC’s Andrew Marr Show.
“Nobody can pretend there isn’t an ongoing problem in the Labour Party with antisemitism.”
Two of the former staffers are themselves planning to take legal action against Labour because they say Labour defamed them in its response to their interviews.
The party had said the testimony came from “disaffected former officials” opposed to Mr Corbyn’s leadership who had “personal and political axes to grind” casting doubt on their “credibility” as sources.
Media lawyer Mark Lewis, who is acting for the pair, told The Observer: “These are very serious libels. Those representing the Labour Party have acted in a way that set out to destroy the reputations of the whistleblowers.”
A Labour spokesperson called them “justified statements of opinion”.
They added: “The Labour Party takes all complaints of antisemitism extremely seriously and we are committed to challenging and campaigning against it in all its forms.
“All complaints about antisemitism are fully investigated in line with our rules and procedures and any appropriate disciplinary action is taken.
“The rate at which antisemitism cases are dealt with has increased more than four fold since Jennie Formby became general secretary.”