Labour Party leader Jeremy Corbyn is under fire for agreeing to speak at an event alongside a speaker who once called for a Jewish journalist’s throat to be cut.

Corbyn is scheduled to speak at a conference in September organised by the far-left group Momentum, The Independent reported Thursday. The conference will be held at the same time as and less than a mile from the official Labour Party conference.

Among the speakers at the Momentum event is Richard Seymour, a far-left blogger who last year wrote of Josh Hasten, an Israeli writer reporting on anti-Jewish attacks in Israel, “F**k him, they should cut his throat.”

Katie Green, a chair of the campaign of Corbyn’s rival for party leadership, Owen Smith, said: “These kind of violent and deeply offensive remarks make a mockery of Jeremy’s ‘kinder, gentler politics.’ Jeremy should be condemning his comments.”

Corbyn, who has called Hezbollah and Hamas “friends,” has been accused of fostering an atmosphere of anti-Semitism in the party.

His planned appearance at the rival Momentum conference is seen as another sign of a deep divide within Labour, which was rocked by England’s recent vote to exit the European Union and allegations of anti-Semitism among numerous party leaders.

The main Labour conference is also in disarray after party leaders decided to cancel a deal with the G4S security firm because of its business ties with Israeli prisons. Organisors are worried they will not have a replacement firm in place in time for the event.

On Wednesday, Smith sparked controversy by saying he would be prepared to engage in peace talks with the Islamic State terrorist group if it were prepared to negotiate. (JTA)