Jess Phillips and three other Labour MPs dramatically quit the party’s frontbench in order to vote for a ceasefire in Gaza, in a major blow to Keir Starmer’s authority.
At least two others defed Mr Starmer to back a call for an immediate cessation in the fighting.
Yasmin Qureshi, the shadow women and equalities minister and MP for Bolton South, was the first to resign. She said: “The scale of bloodshed in Gaza is unprecedented. Tonight, I will vote for an immediate ceasefire.
“We must call for an end to the carnage to protect innocent lives and end human suffering. With regret, I have stepped down as shadow women and equalities minister.”
Afzal Khan, the shadow minister for exports and MP for Manchester Gorton , was the second frontbencher to rebel, saying supporting a ceasefire was “the very least we can do”.
The third, Paula Barker, shadow minister for devolution and the English regions and MP for Liverpool Wavertree, said she would be following “my conscience”.
The Labour leader has called for a humanitarian pause in the war and warned a full-scale ceasefire would only “embolden” Hamas to regroup and plan more atrocities.
Labour MPs have been ordered to back the party’s amendment to the King’s Speech later, which calls for longer humanitarian pauses in Gaza.
They are also under three-line whip to abstain on the SNP’s amendment calling for a ceasefire, meaning shadow ministers are almost certain to be sacked if they rebel to support it.
While more than 70 Labour MPs have publicly backed calls for a ceasefire in Gaza, a Labour spokesperson said that a Commons vote was a different matter, adding: “This is a whipped vote and every MP knows what the consequence of that means.”
During Wednesday’s Commons debate, Naz Shah became the first Labour frontbencher to tell MPs that she intended to support “the amendment which seeks an immediate ceasefire”.
She was followed by shadow minister Helen Hayes, who told the Commons that “a ceasefire is surely the minimum we should be demanding in the face of such horrific suffering”, adding: “My conscience tells me I must call for a ceasefire today.”
With a host of other frontbenchers expected to vote for the SNP amendment, Sir Keir was braced on Wednesday for one of the significant tests he has faced since winning the leadership.
Some reports suggested that, rather than resign ahead of the vote, frontbenchers had been advised by colleagues to merely cast their vote and see whether Sir Keir would sack them.
Labour’s decision not to back a ceasefire has also prompted the exodus of a series of councillors from the party, and Sir Keir was forced to hold a crunch meeting last month with a group of Muslim Labour MPs to address anger over his handling of the crisis – including comments in which he appeared to back the cutting of power and water to Gaza.
However, frontbencher Imran Hussain ultimately resigned “with a heavy heart” last week, saying he was quitting his role as a shadow minister to be able to “strongly advocate” for a ceasefire.
The Commons showdown came as Israel’s forces entered Gaza’s al-Shifa hospital, which Israel insists sits atop a military headquarters used by Hamas. Medics have warned of more civilian casualties, with troops’ encirclement of the hospital in recent days already blamed for the deaths of dozens of patients.