LONDON - British Prime Minister Boris Johnson said on Tuesday it was a “serious business” when the chief rabbi criticized the opposition leader Jeremy Corbyn for failing to root out anti-Semitism from the Labor party.

“All I will say about that is I do think it is a very serious business when the chief rabbi speaks as he does,” Johnson said in response to a question from a reporter on Chief Rabbi Ephraim Mirvis’s attack on Corbyn.

“I’ve never known anything like it and clearly it is a failure of leadership on the part of the Labor leader that he has not been able to stamp out this virus in the Labor Party.”