Keir Starmer has said he has a “gut feeling” that comments by one of his MPs were antisemitic.
Labour suspended the whip from Diane Abbott after she wrote to the Observer newspaper suggesting Jewish people were not subject to the same racism as other minorities.
The letter stated that Jewish, Irish and traveller communities have experienced “prejudice”, but added: “This is similar to racism and the two words are often used as if they are interchangeable.”
Ms Abbott had added: “It is true that many types of white people with points of difference, such as redheads, can experience this prejudice. But they are not all their lives subject to racism.”
Speaking on Thursday morning Sir Keir said the contents of the letter were "shocking".
Asked on ITV's GMB programme what he thought of the comments, the Labour leader said: "There's an investigation going on now, but I'm not going to accept that there's a hierarchy there. We need to look what she said and come to a decision on that."
But pushed, he said: "My gut feeling is that it's shocking, my gut feeling is that it's antisemitic, and that I'm determined to change the Labour party so that the Labour party and antisemitism are not mentioned in the same sentence."
Ms Abbott had swiftly apologised for the comments and said an "initial draft" of the letter had been sent by mistake.
“I wish to wholly and unreservedly withdraw my remarks and disassociate myself from them,” said the Labour MP. “The errors arose in an initial draft being sent. But there is no excuse, and I wish to apologise for any anguish caused.
Ms Abbot added: “Racism takes many forms, and it is completely undeniable that Jewish people have suffered its monstrous effects, as have Irish people, Travellers and many others. Once again, I would like to apologise publicly for the remarks and any distress caused as a result of them.”
The Labour left-winger had been responding to a newspaper column by Tomiwa Owolade arguing that that Irish, Jewish and Traveller people all suffer from racism.
Also speaking on Thursday morning Sir Keir said: “Let me acknowledge what Diane Abbott has had to put up with for many, many years. I think she's probably suffered more abuse, obviously racial abuse, than any other person in public life, certainly any other politician. That is terrible and it should be condemned and called out and she should be supported in that.
“But alongside that, or despite that, what she said in a letter on Sunday is to be condemned. It is suggesting a sort of hierarchy of racism which I do not accept. The first thing I said when I became Labour leader, my very first speech, my acceptance speech, is that I would tear antisemitism out by its roots.”
Ms Abbott had written: “In pre-civil rights America ... Irish people, Jewish people and Travellers were not required to sit at the back of the bus. In apartheid South Africa, these groups were allowed to vote.”
The MP for Hackney North and Stoke Newington added: “And at the height of slavery, there were no white-seeming people manacled on the slave ships.”
The Board of Deputies of British Jews said Ms Abbott’s letter “was disgraceful and her apology is entirely unconvincing”, while the Jewish Labour Movement said it “regretfully” supports the decision to suspend the whip.
Labour is now investigating the comments and will decide the MP’s future.
