Jeremy Corbyn has admitted having been a member of a controversial private Facebook group about Palestine but denied ever seeing anti-Semitic posts.
The British Labour party is investigating after claims abusive messages about Jews were exchanged on the forum emerged.
Mr Corbyn said he was signed up to the group without his knowledge, but later exchanged messages on it.
During a visit to Alfreton, Derbyshire, England, he told the Press Association: "I was joined on to that group without knowing it in probably about 2013/14.
"I removed myself from the group in 2015. I replied by Facebook message to a couple of things about a suggestion on the vote on recognising Palestine, which I supported, and inviting a doctor to speak at an event.
"I have never trawled through the whole group. I have never read all the messages on it. I have removed myself from it.
"Obviously, any anti-Semitic comment is wrong. Any anti-Semitism in any form is wrong."
The Campaign Against Anti-Semitism published screenshots of messages said to have been posted on the Palestine Live group.
Among the comments exchanged are claims about Israeli involvement in the 9/11 terrorist attacks as well as links to neo-Nazi groups postings.
Mr Corbyn said the party "doesn't tolerate" anti-Semitism "in any form" and he would have challenged any abusive posts if he had seen them.
"Had I seen it, of course, I would have challenged it straight away but I actually don't spend all my time reading social media," he said.