Jeremy Corbyn refused four times to apologise to the Jewish community over how Labour had handled allegations of anti-Semitism within its ranks and insisted the country’s Chief Rabbi was wrong in his sharp criticism of it.

Under fierce questioning from the BBC’s Andrew Neil the party leader also defended his decision to stay neutral as Prime Minister in a future EU referendum, saying it would be an “adult and sensible way to go forward”.

And on footing the near £60 billion cost of compensating millions of so-called WASPI women for their losses due to the change in the state pension age, Mr Corbyn admitted the money might have to be found from borrowing.

In his most difficult day of the election campaign so far, the Labour leader was rocked by an unprecedented intervention by a religious leader when Ephraim Mirvis accused him of sanctioning the “poison” of anti-Semitism in his party, which, he claimed, had proved Mr Corbyn was “unfit for high office”.

The Chief Rabbi dismissed the Leader of the Opposition’s insistence that Labour had dealt with all allegations of anti-Semitism as a “mendacious fiction” and claimed the way the party had approached the issue had been “incompatible" with British values.

Mr Mirvis’s criticism came on the day the Opposition launched its Race and Faith manifesto aimed at showing Labour’s commitment to equality and human rights.

Asked by Mr Neil how he responded to the Chief Rabbi’s attack, Mr Corbyn replied: "I'm looking forward to having a discussion with him because I want to hear why he would say such a thing."

Challenged over Mr Mirvis's allegation that Labour's claim to be doing everything to tackle Jewish hatred in its ranks was a "mendacious fiction," the Labour declared: “No, he's not right. Because he would have to produce the evidence to say that's mendacious."

Mr Corbyn explained he had "developed a much stronger process" and had removed members who had been anti-Semitic.

He also denied the blight of racism had increased after he took over leadership of the party, saying: "It didn't rise after I became leader. Anti-Semitism is there in society, there are a very, very small number of people in the Labour Party who have been sanctioned as a result about their anti-Semitic behaviour."

But when pressed if he would apologise for the way the anti-Semitism row had been handled within Labour, the party leader repeatedly refused to do so.

He said: "We will not allow anti-Semitism in any form in our society because it is poisonous and divisive, just as much as Islamophobia or far-right racism is."

Mr Corbyn was also pressed over his plan to broker a Leave deal with the EU and offer it alongside Remain in a referendum within six months of taking power while personally staying neutral.

"I will be the honest broker who will make sure the referendum is fair and make sure the Leave deal is a credible one," declared the Labour leader. "That seems to me an adult and sensible way to go forward," he insisted.

But he was unable to say who in a Labour Cabinet would campaign for his Brexit deal given most of his senior colleagues have already expressed their eagerness to campaign for Remain.

On his taxation plans, Mr Corbyn denied that a significant part his income tax base would leave the country if he took power.

"No, it doesn't crumble at all," he said. "They can see all around them the crumbling of public services and the terrible levels of child poverty that exist across Britain. There is no reason why they would have to leave the country and they shouldn't."

The party leader insisted a Labour Government was “not going to willy-nilly borrow” but when pressed on how it would pay for the near £60bn to compensate the WASPI women, admitted it would either be from Government reserves or, “if necessary,” from borrowing.

In response, Michael Gove for the Conservatives said: “Jeremy Corbyn won’t be straight with the British people.

“He won’t apologise for his failure to stamp out racism in his party. He can’t say whether he backs Leave or Remain in his own second referendum. He can’t answer how he would pay for his fantasy plans for the country or how he’d keep Britain safe.

“All that’s on offer from Prime Ditherer Corbyn is more Brexit delay, the chaos of another two referendums and lasting damage to our economy, leaving hardworking taxpayers to foot the bill,” added the Cabinet Office Minister.