He said that Mr Corbyn gave “support to racists, terrorists and dealers of hate who want to kill Jews and remove Israel from the map.
“When he implies that, however long they have lived here, Jews are not fully British, he is using the language of classic pre-war European antisemitism.
“When challenged with such facts, the evidence for which is before our eyes, first he denies, then he equivocates, then he obfuscates.
“This is low, dishonest and dangerous. He has legitimised the public expression of hate, and where he leads, others will follow.
“Now, within living memory of the Holocaust, and while Jews are being murdered elsewhere in Europe for being Jews, we have an antisemite as the leader of the Labour Party and her majesty’s opposition.
“That is why Jews feel so threatened by Mr Corbyn and those who support him.” Labour described the comments as “absurd and offensive”, insisting Mr Corbyn had not used “Zionist” as a synonym for Jews.
While Lord Sacks’ words triggered an angry backlash on social media from Corbynites, rabbis told the JC they agreed with him.
Rabbi Moshe Freedman of the New West End Synagogue said Lord Sacks was “absolutely right. Our community has a better understanding of history than Jeremy Corbyn ever will. It is he and his followers who need to learn.
“People need to listen. There is a lot of dissonance among Corbyn supporters. The response from the Labour Party is unsurprising and typically dismissive. It is really troubling.”
Rabbi Alex Chapper of Borehamwood and Elstree Synagogue said he agreed with Lord Sacks that “Corbyn’s comments are the most offensive.
“We can no longer sit on the fence. There is a line and that has been firmly crossed. He is quite rightly highlighting that much of what Corbyn says and does has a tendency to verge on antisemitism.”
Rabbi Chapper called on the Labour leader to “set about repairing the relationship with the community through actions and not words.”
Rabbi Laura Janner-Klausner, Reform Judaism’s senior rabbi, said Mr Corbyn’s statement about Zionists and irony had “pointed at Jews as foreigners who can’t play the English Game.”
She said the fact that Lord Sacks felt the need to draw a comparison to Enoch Powell shows “what a nightmare Corbyn would be. It is not rivers of blood, but it is not Jews being treated as equal citizens either. Corbyn is a liability and to have him as a world leader would be a farce.”
She described the Labour Party’s response as “childlike. When someone criticises you the appropriate thing to do is listen and think about what they have said instead of reacting defensively immediately.
“It is time to start having some serious discussion here instead of playing pantomime politics.”
Reform Rabbi Jonathan Romain of Maidenhead Synagogue said that, while the Enoch Powell analogy may have shocked people, “it accurately reflected what most British Jews feel. It was certainly successful in drawing attention to the total despair, bordering on horror, which is prevalent in the community.
“As more and more evidence of Corbyn’s past emerges, none of which bolsters his claim to be a peace-maker,” it acted as evidence of his “one-sided standpoint and personal prejudice.”
But Rabbi Alexandra Wright, the senior rabbi at the Liberal Jewish Synagogue in St John’s Wood, said Lord Sacks’s comments were “irresponsible and dangerous”.
“Powell’s speech was devastating, a stain on British history, and has had a malign and lasting effect on the way race and migration are addressed or ignored,” she said.
“The former Chief Rabbi has appropriated the speech in a way that is deeply inappropriate and that serves one purpose only: to separate us as Jews from the rest of society. We are, in the words of Edie Friedman, ‘othering ourselves’.”
