Momentum founder Jon Lansman has said he agrees with Chief Rabbi Ephraim Mirvis over the "importance of countering racism" - but says he has been left "upset" by the "one-sided" nature of his intervention.
Speaking to the JC at Labour's Race and Faith manifesto launch, Mr Lansman said: "It upsets me as a Jew that the Chief Rabbi intervened in a way that lacks balance."
The veteran left winger said he believed Rabbi Mirvis had wanted to issue a wider warning about "the importance of countering racism - whoever says it and whoever is the victim."
But he added: "I'm sorry he didn't put what he had said on this in a more balanced way."
Mr Lansman said: "I'm very upset by this. I'm disappointed in the one-sidedness of the overall message. I think it diminishes anti-racism by being so one-sided."
A staunch supporter of Jeremy Corbyn, Mr Lansman said that "one of the most depressing things" was that the message about the need to counter racism in all political parties "would probably disappear after a couple of days".
He said he also found suggestions that Labour was not tackling antisemitism in the party properly "frankly offensive".
He pointed to his article for the JC last week and said he "spent quite a lot of my time" dealing with cases in a proper manner.
Mr Lansman said he accepted that the problem over antisemitism on the left was "not all about Israel as some in Labour think".
He added that the party's election manifesto was "actually good on Israel".
The manifesto "commits to a two-state solution - a secure and viable Israeli state alongside a secure and viable Palestinian state," he said. "And that is right."
