Jeremy Corbyn faces the prospect of shadow cabinet resignations as early as next month after Hilary Benn refused to say whether he would quit the front bench if the Labour leader attends the Stop the War Coalition's Christmas fundraising party.
The anti-war pressure group came under intense fire from Labour MPs after it posted a blog on its website titled: "Paris reaps whirlwind of western support for extremist violence in Middle East".
Mr Benn, the shadow foreign secretary, condemned the decision to post the blog post, which has now been deleted from its site but still available to view online.
He said it was "wholly wrong," adding: "This is not the fault of the French and I am glad that tweet was deleted. It is the fault of the attackers. They represent a threat to all of us and we have to take effective action."
Asked whether he would step down if Mr Corbyn went ahead with his invitiation to appear as Stop the War's "special guest" at its Christmas fundraising event, Mr Benn twice refused to give an answer, instead saying: "That is a decision for Jeremy".
The blog post was just one of several events that led to a fiery meeting of the Labour Parliamentary party on Monday night, where MPs attacked Mr Corbyn over his response to the terror attacks in Paris.
One shadow minister branded the Labour leader a "f****** disgrace" for a series of comments he has made since 129 people were killed by Isis terrorists in Paris.
He has questioned of the legality of the drone strike that is believed to have killed Jihadi John, his decision to rule out a free vote for Labour MPs on bombing Isis in Syria and his opposition to the "shoot-to-kill" policy if police are given the chance to shoot down a terrorist in London.
Mr Corbyn also warned on Monday that bombing Syria might simply cause “yet more conflict, more mayhem and more loss”.
His firm opposition to military intervention in Syria is at odds with some moderates in his party, with an estimated 50 Labour MPs believed to support the Government's wish to bomb Isis targets in Syria.
Following the meeting a shadow minister said: “He doesn’t answer anything. He got roasted."
A spokesperson for Mr Corbyn said that those who express critical views “volubly” were in the minority and that the shadow cabinet was united on blocking military action in Syria.
"Without the American crime of aggressive war against Iraq – which, by the measurements used by Western governments themselves, left more than a million innocent people dead – there would be no ISIS, no “Al Qaeda in Iraq”."
It added: "What has been the result of these interventions? A hell on earth, one that grows wider and more virulent year after year."
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