Labour will act to block people not fit to be MPs, shadow defence secretary John Healey has pledged, as the party struggles to deal with an ongoing row about comments made by its candidates.

He insisted the party practiced “due diligence” when picking its candidates to be MPs but added: “You can’t see everything, everywhere.”

He said the public deserved candidates who “meet the highest standards”.

The Jewish Labour Movement said it had not been Labour’s “finest hour”.

In the past week, the party has suspended two of its parliamentary candidates, over comments they allegedly made at a meeting.

Azhar Ali had been the party’s candidate in the Rochdale by-election, due to take place on 29 February.

Over the weekend, the Mail on Sunday reported that Mr Ali had suggested Israel “allowed” the 7 October attacks by Hamas, at a meeting attended by Labour members and councillors.

Mr Ali “unreservedly apologised” for his remarks and Labour said it would continue to campaign for him.

However, the party subsequently withdrew support after the Daily Mail reported Mr Ali had blamed “people in the media from certain Jewish quarters” for the suspension of MP Andy McDonald from Labour.

On Tuesday, the Guido Fawkes website published audio allegedly from the same meeting, in which Graham Jones, the Labour candidate in the Hyndburn constituency, used an expletive to describe Israel and said British people who fight in the Israel Defense Forces “should be locked up”.

Mr Jones was suspended by the party and is now facing an investigation.

Mr Healey told the BBC’s Today programme, Mr Jones’ comments had been “unacceptable”.

Asked if all Labour councillors who were at the meeting should also be suspended, Mr Healey said the party would “follow the hard evidence that comes to us”.

“What is important is, if new info comes to light – as in this case – we will act to investigate, we will act to block those who are not fit to serve as MPs.”

He said that withdrawing support from its candidates was “regrettable but essential” and that Labour would put the “country’s interest before party interest”.

The shadow minister added that he “really feels” for the people of Rochdale who want to vote Labour. “We have left them without a candidate,” he said.

Although Labour has withdraw its support, electoral rules mean Mr Ali will remain on the ballot paper as the party’s candidate.

Chair of Jewish Labour Movement Mike Katz has called for all councillors, MPs or parliamentary candidates who were present at the meeting to be suspended if they can be identified.

Mike Katz also welcomed the “swift” suspension of Mr Jones adding: “To be in that meeting, to have heard that rhetoric, to have been a bystander, to have not called it out at the time, or indeed subsequently, that really calls into play your judgement.”

Mr Katz added that the party owes people in Rochdale an apology for having selected Mr Ali as their by-election candidate prior to his suspension.

“This has not been the party’s finest hour – we have huge lessons to learn but the direction of travel is very much upwards, it’s very much in the right direction.”

He said it was now “highly likely” that George Galloway will be elected.

The former Labour and Respect MP is running in the by-election for the Workers Party of Britain and has focused his campaign on the conflict in Gaza.

Conservative Housing Minister Lee Rowley told the BBC the situation with Mr Ali had been “a complete mess”.