Jeremy Corbyn attended an event run by Holocaust denier Paul Eisen’s charity in 2013, despite his claim not to have had any contact with the group in recent years.
The Labour leadership frontrunner attended a Deir Yassin Remembered commemoration in St John’s Wood Church, north west London, in April 2013.
The group was founded by Mr Eisen.
In an interview on Channel 4 News on Monday, Mr Corbyn said he had met Eisen 15 years ago, before it was publicly known that the activist was a Shoah denier.
But he added: “I have no contact whatsoever now with Paul Eisen and Deir Yassin Remembered. I did attend a number of events concerning DYR some years ago, I think two or three of them. The only donation would have been in a collection bucket going round the room, that’s all.
“Fifteen years ago he certainly was not a Holocaust denier, had he been a Holocaust denier or stated he was, I would have had nothing to do with him. Obviously Holocaust denial is vile and wrong.”
However a post on the DYR website shows Mr Corbyn attending the April 2013 event. It is not clear whether Mr Eisen was also at the commemoration.
Mr Eisen had written a blog four months earlier titled “How I became a Holocaust denier”.
In it he wrote: “I question that there ever existed homicidal gas-chambers. I question the figure of six million Jewish victims of the Nazi assault and I believe that the actual figure was significantly less.”
Mr Corbyn's fellow Labour MP Gerald Kaufman also attended the April 2013 commemoration.