JEREMY Corbyn’s closest ally has said the spiralling row over anti-Semitism within Labour has shaken the party “to the core”.

Shadow Chancellor John McDonnell, who has reportedly challenged Mr Corbyn over his handling of the issue, said the party needed to resolve it as soon as possible.

There are fears the row, which has been growing on for months, could dog the party all summer and overshadow its autumn conference in Liverpool.

Mr McDonnell told the BBC: “None of us fail to appreciate the way this has upset people, including ourselves. It’s shaken us to the core really. But we’ll resolve it. We’ve got to.

“We’ve got to resolve it within the Labour party certainly. But also, the members of the Jewish community are really suffering out there.

“We’ve had a massive increase in attacks on the Jewish community, daubing of cemeteries, it’s appalling that Jewish schools have to have security guards as well.

“We’ve got to resolve the issue in our party and then get out there to assist the Jewish community, campaign against anti-Semitism within our society overall.”

He was speaking after Mr Corbyn was forced to apologise for appearing on platforms with people making anti-Semitic remark, saying he “completely rejects” their views.

The Campaign Against Anti-Semitism, which has asked the UK Equality Commission to investigate whether Labour is “institutionally anti-Semitic” highlighted a case from 2010.

Mr Corbyn, then a backbench MP, hosted an event at the House of Commons on Holocaust Memorial Day called “The Misuse of the Holocaust for Political Purposes”.

One speaker, Holocaust survivor Hajo Meyer, who died in 2014, compared Israeli policy to the Nazi regime, while another, Palestinian activist Haidar Eid, told the meeting: “The world was absolutely wrong to think that Nazism was defeated in 1945. Nazism has won because it has finally managed to Nazify the consciousness of its own victims.”

Mr Corbyn said views were expressed which he did not “accept or condone”.

He said: “In the past, in pursuit of justice for the Palestinian people and peace in Israel/Palestine, I have on occasion appeared on platforms with people whose views I completely reject. I apologise for the concerns and anxiety that this has caused.”

Labour MP Louise Ellman said she was “exceedingly disturbed” and “absolutely appalled” to hear of Mr Corbyn’s presence at the event.

Labour MP John Mann, a long-standing critic of Mr Corbyn, also told the BBC that hosting such an event breached anti-Semitism rules and “breaches any form of normal decency”.

He said: “I've no idea how he got himself into that situation, but I'm glad he has apologised and on the back of that apology is the opportunity to do something significant.”

The row over anti-Semitism within labour has escalated since the party’s ruling National Executive Committee refused to adopt a standard international definition of anti-Semitism.

Instead, when drawing up a code of conduct on the subject, it omitted key parts of the International Holocaust Remembrance Alliance definition referring to Israeli policy.

Israeli policy, particularly with regard to the Palestinians, has long been the target of criticism by many on the Corbyn-supporting Left of the party.

The row worsened this week when a leaked tape emerged of Corbyn-supporter Peter Willsman ranting about Jewish “Trump fanatics” and the falsifying of social media posts at the same NEC meeting which endorsed the code.

He apologised but was not disciplined, despite two complaints about his comments.

He is facing calls to abandon his bid to be re-elected to the NEC.