Len McCluskey risks being “part of the problem” in the fight against anti-Semitism within Labour, Sir Keir Starmer has suggested as the party edged closer to civil war.
The shadow Brexit secretary said there was a need to “stop those that are denying there is even a problem” as he called for a “cultural change” in the party’s approach to the issue.
Mr McCluskey, the general secretary of Unite and Jeremy Corbyn’s closest union ally, on Wednesday warned five "Corbyn-hater" Labour MPs that they would be "held to account" after he accused them of whipping up a row over anti-Semitism to "smear" the Labour leader.
Mr McCluskey said Wes Streeting, John Woodcock, Neil Coyle, Chris Leslie and Ian Austin had used anti-Semitism to "toxify" the party.
Sir Keir told BBC Radio 4’s Today programme: “I disagree with Len McCluskey. Jeremy Corbyn has made it clear and it is obvious that we have got a problem with anti-Semitism.
“We have got to deal with it robustly and effectively.
“Part of that is the disciplinary procedure which needs to be much quicker and much more effective but there is also a cultural question and part of that cultural question is to stop those that are denying there is even a problem.
“That is part of the problem so I am afraid I disagree with Len on this.”
Writing in the New Statesman, Mr McCluskey said he accepted “there are anti-Semites in the Labour Party – few in number for sure, but any is too much”.
He said that “raising the issue of combating their views is not merely legitimate, but essential”.
Sir Keir said he believed Labour was “turning a corner” on the issue.
He said: “I think that we need to look at what Jeremy Corbyn has asked Jennie Formby to do, the new general secretary.
“He has asked her to make it a priority and he is right to do so and she has made it clear that the denial that it is a problem is part of the problem.
“I do think that we are, and I hope we are, turning a corner on this.
“Much more effective disciplinary action but a cultural change that makes it clear that simply denying there is a problem is part of the problem.”
Mr Corbyn has said he is committed to tackling anti-Semitism but Mr McCluskey's comments will undermine the Labour leader's attempt to change the narrative.
Labour is investigating 90 cases of alleged anti-Semitism by its members, and has suspended 20 members in the past fortnight.