That stark warning came from Labour peer Lord Sugar yesterday during an antisemitism debate in the House of Lords.

Talking about Mr Corbyn’s failure to deal with his party’s antisemitism crisis, he said: “Mr Corbyn simply does not care — we mean nothing to him.

“There are 250,000 Jews in this country... those votes are a drop in the ocean.

“What kind of leader is he to not take the party by the scruff of the neck and make it see sense and end this once and for all.

“Terminate the obsession of the hard left with Israel and ‘Palestine’ and focus on far more pressing matters like Brexit and jobs.”

Lord Sugar said there was no smoke without fire.

He added: “I request that the British government extinguish the flame and ensure that Jeremy Corbyn does not become the leader of our country — that would be the day Britain dies.” The hour-long debate was over-subscribed, meaning that all speakers were limited to just two minutes.

But another debate is due before the end of the year.

One of those able to speak was Lord Mendelsohn.

The Labour peer said: “The leader of my party, Jeremy Corbyn, has been a perpetrator of antisemitism. He needs to reflect very carefully on this.

“The community has been alert since the Second World War to all manifestations of antisemitism.

“The approach of the party will not be enough.

“Don’t blame the victim — it happens in our party because it is a problem in our party.”

And former Chief Rabbi Lord Sacks said: “Most antisemites do not think of themselves as antisemites.

“Antisemitism is the hardest of all hatreds to defeat.

“It is not only Jews who are at risk, so too is humanity.”

Lord Palmer called for antisemitism on social media “and on our streets” to be made “legally unacceptable”.

Lord Alton called antisemitism a “virus”, which starts with the Jews, but spreads “like a contagion” to others.

He added that there was an “urgent need to confront antisemitism” because it “never ends with the Jews”.

Others who spoke included Baroness Altman, Baroness Deech, Lord Hunt and Lord Popat.

The latter, a Hindu, said: “I am a Zionist. I am also a critic of Israeli policies.

“Once you begin to challenge a country’s right to exist, then you have to ask yourself what your motivation is.

“Is it purely a moral reaction to the government or is it driven by deeper hostility? Enough is enough.

“When my Jewish friends are afraid of openly identifying as Jewish and fearing for their safety, we have a duty to listen and ask how it has come to this, why it has come to this and what we are going to do about this.”