The Labour leader apologised for “hurt and pain” caused by instances of anti-Semitism in the party as he faced a wave of criticism from within the Jewish community.
The letter to the Board of Deputies of British Jews and Jewish Leadership Council came after the organisations launched a stinging attack on Mr Corbyn, accusing him in an open letter to Labour MPs of siding with anti-Semites “again and again”.
The groups protested outside Parliament yesterday, along with members of the Jewish community, before delivering the letter to a meeting of Labour MPs and peers at which concerns about anti-Semitism were expected to be raised – although it was not anticipated that Mr Corbyn would attend.
He said: “I am sincerely sorry for the pain which has been caused, and pledge to redouble my efforts to bring this anxiety to an end. I must make it clear that I will never be anything other than a militant opponent of anti-Semitism.”
He said there needed to be a deeper understanding of what constitutes anti-Semitism in the Labour Party, and apologised for “not having studied the content” of an anti-Semitic mural he defended against removal in 2012.
Mr Corbyn also said: “I acknowledge that anti-Semitic attitudes have surfaced more often in our ranks in recent years, and that the party has been too slow in processing some of the cases that have emerged … we will work to speed up procedures, to deal with cases of anti-Semitic abuse or attitudes.”
He said criticism of Israel in relation to the “continuing dispossession of the Palestinian people” cannot be avoided, but added: “Nevertheless, comparing Israel or the actions of Israeli governments to the Nazis, attributing criticisms of Israel to Jewish characteristics or to Jewish people in general and using abusive phraseology about supporters of Israel all constitute aspects of contemporary anti-Semitism.”
In their letter, Jewish leaders took aim at Mr Corbyn personally, saying he was “repeatedly found alongside people with blatantly anti-Semitic views” but “claims never to hear or read them”.
The Board of Deputies and Jewish Leadership Council also wrote: “Today, leaders of British Jewry tell Jeremy Corbyn that enough is enough.”
They said there was a “repeated institutional failure” to properly address Jewish concerns and to tackle anti-Semitism.
“We conclude that he cannot seriously contemplate anti-Semitism, because he is so ideologically fixed within a far-left worldview that is instinctively hostile to mainstream Jewish communities.”