The Home Secretary condemned the contents of a tweet about the new Tory leader that was shared by a Labour backbencher.
Yvette Cooper branded a retweet by a Labour MP about Kemi Badenoch as “appalling”.
Dawn Butler shared a post from Nigerian-British author Nels Abbey which described Ms Badenoch’s election as the new Tory leader as a “victory for racism”.
Ms Butler went on to delete the retweet offering “tips for surviving the immediate surge of Badenochism” which is said was “white supremacy in blackface”.
The Home Secretary said she had not seen the post, but when read excerpts from it, she told LBC: “I clearly strongly disagree with that.”
Asked whether the words in the post had a “racist sentiment”, Ms Cooper added: “The words that you have read out are clearly appalling and I would strongly disagree with them.
Home Secretary Yvette Cooper
“So, I haven’t seen the post. I don’t know the circumstances around it but I think we should congratulate Kemi Badenoch on her election.
“I will continue to disagree with her on all sorts of issues, but, nevertheless, I congratulate her on her election.”
There have been calls for Ms Butler, who represents Brent East, to lose the Labour whip over the retweet.
Pressed on why no action had been taken, Ms Cooper said: “As I said, I haven’t seen the post and I think those sorts of issues around party issues, those are always ones for the whip.”
Ms Butler has faced criticism from Tory MPs over the retweet after Ms Badenoch won the Conservative leadership race on Saturday.
Huntingdon MP Ben Obese-Jecty said Ms Butler was “not alone on the Government benches in holding this view of Kemi”.
He said: “This will be a test to see whether Keir Starmer removes the whip, or effectively condones Butler’s abhorrent approval of this smear.”
Other Labour figures, including Sir Keir Starmer and Foreign Secretary David Lammy, hailed Ms Badenoch’s election as the first black leader of a major UK party as a historic moment.