Labour has seen an increase in members “attracted towards conspiracy theories”, the founder of Momentum has said.
Jon Lansman, who set up the influential grassroots pro-Jeremy Corbyn campaign group, said Labour had a “major problem” with anti-Semitism. “We underestimate the scale of it,” he told BBC Radio 4′s Today programme.
Anger at perceived failures of the leadership to deal with the spread of anti-Semitism in the party was a factor in the decision of nine Labour MPs to quit last week.
Dudley North MP Ian Austin, who resigned from Labour on Friday, said he was “ashamed” of the party which had developed a “culture of extremism, anti-Semitism and intolerance” under Corbyn.
The Labour leader denied there was a “wide scale” problem of racism in the party.
Lansman, who is Jewish and a close ally of Corbyn, also denied accusations the party was ” institutionally anti-Semitic”.
But he added: “We have a much larger number of people with hardcore anti-Semitic opinions which unfortunately is polluting the atmosphere in a lot of constituency parties and in particular online.”
He said while members of all parties believed in “conspiracy theories”, Labour had a particular problem due to its size.
“The Tory party is a smaller party and an elderly party and the role of social media in fomenting and spreading some of the poison is therefore more of a problem in the Labour Party” he said.
Lansman later added on Twitter: “Of Labour’s 500,000 members perhaps a few hundred are hardcore antisemites. If we improve our processes, we can make sure they are kicked out of the party.”
Shadow chancellor John McDonnell has acknowledged “fiercer” action is needed on anti-Semitism.
“I think there’s been a lot of listening but not enough action. That’s the problem,” he said last week.