The UK Labour Party must “root out anti-Semitism completely, totally” former party leader and prime minister Tony Blair has warned.

Mr. Blair was speaking Monday on Israeli television and took the opportunity to excoriate the party he lead for for 13 years, saying the crisis engulfing Labour was something that would never have happened in his time at the helm.

“I’m extremely sad about it, and anxious about it, and also very determined that the Labour Party should take the action necessary to root out anti-Semitism completely, totally. There should be zero tolerance towards it,” Blair told Channel 10 news.

“It’s one of these things that if you allow it to take root at all within a political party, it’s hard then to uproot it,” he said. “This is a situation, frankly, I could not even have imagined when I was leader of the Labour Party.”

Mr. Blair went on to say he was distressed on behalf of the Jewish community and joined the chorus of those demanding Labour take action.

“I’m afraid it is a problem,” he said. “The leadership has now said that they’re going to take the necessary action. But they really need to do that.”

The warning came as Labour entered the second week of an ongoing controversy over allegations of institutional anti-Semitism amongst the membership in general and leader Jeremy Corbyn in particular.

Within hours of Mr. Blair speaking, Mr. Corbyn was criticised for attending an event organised by Jewdas – a hard left Jewish group critical of more mainstream Jewish organisations.

This is a payer taken from Jewdas’s Seder night. It starts with the words ‘Please God, smash the State of Israel’

This is who Corbyn met with! pic.twitter.com/hByvKwLnPK — SussexFriendsIsrael (@SussexFriends) April 3, 2018

Jewdas, which describes itself as a “radical” and “alternative” Jewish collective, is at odds with mainstream Jewish groups over allegations of anti-Semitism in Labour.

It has accused the Jewish Board of Deputies, Jewish Leadership Council and Jewish Labour Movement of “playing a dangerous game” and previously dismissed anti-Semitism allegations as right-wing smears.

One Labour MP called his actions “irresponsible and dangerous,” the BBC reports.

Last week Jewish leaders and thousands of their supporters took to London’s streets to voice their opposition to the rise of anti-Semitism in the Labour Party.

That march came in the wake of polling which shows that British Jews have been abandoning Labour since the election of Mr. Corbyn, and a recent survey revealed that four in five believe the party harbours anti-Semites in its ranks.