Appearing alongside Manuel Hassassian, the Palestinian Authority representative in Britain, Corbyn described how a recent speech given by the envoy had been criticised by Zionists at the event.
He said, "[Hassassian's words] were dutifully recorded by the thankfully silent Zionists who were in the audience on that occasion and then came up and berated him afterwards for what he'd said. So clearly two problems. One is that they don't want to study history and, secondly, having lived in this country for a very long time, probably all their lives, they don't understand English irony either."
A spokesman for Corbyn claimed he had been referring to a "group of pro-Israel activists" and not singling out Jews, adding he was "opposed to all forms of anti-Semitism".
However, critics said his reference to people who had lived in Britain for "a very long time" appeared to be a specific criticism of Jews.
Corbyn has been publicly condemned by more than a dozen Labour MPs.
Corbyn said: "I am now more careful with how I might use the term 'Zionist' because a once self-identifying political term has been increasingly hijacked by anti-Semites as code for Jews."
