Sir Keir Starmer has insisted he did not threaten the Commons Speaker “in any way whatsoever” to secure a vote on Labour’s stance on Gaza.

Speaking publicly for the first time since it emerged he lobbied Sir Lindsay Hoyle to select Labour’s amendment for the ceasefire debate, he denied turning the screw on the Speaker, insisting he “simply urged” him to enable “the broadest possible” discussion.

But Penny Mordaunt accused him of putting his party’s interests above all else in a blistering attack on the “weak and fickle” leader in the Commons.

She also warned that parliamentary procedure must “never” be upended because politicians are afraid to stand up for what they believe in after Sir Lindsay’s allies said he made the decision partly out of concern for MPs’ safety - as that would mean “democracy has failed and the extremists have won”.

Tory MPs have claimed Sir Lindsay was put under “intolerable pressure” by the Labour Party to break with convention and put its position on the Israel-Hamas conflict to a vote.

The BBC reported that, according to senior Labour figures, the Speaker “was left in no doubt” that the party would “bring him down” after the general election unless he selected the amendment.

But speaking in Sussex on Thursday, Sir Keir said: “I can categorically tell you that I did not threaten the Speaker in any way whatsoever.

“I simply urged [him] to ensure that we have the broadest possible debate so that actually the most important thing, which is what do we do about the situation in Gaza, could be properly discussed by MPs with a number of options in front of them.”

It comes as Sir Lindsay’s future in the prestigious role is on the brink, with more than 50 MPs calling for him to go.

The Speaker agreed to put Labour’s stance to a vote on Wednesday despite the House of Commons clerk explicitly warning him that the approach broke with convention for opposition day debates, prompting claims of bias towards the party he represented as an MP for two decades.

He ended up giving an emotional apology, saying he regretted how his decisions had panned out and promising to meet party leaders to provide reassurances.

Ms Mordaunt, the Commons Leader, said the “shameful” scenes in the House were the result of “party politics” from Labour, labelling Sir Keir “weak and fickle”.

She claimed Sir Keir was “quite happy to do what he knows to be wrong”, suggesting he piled pressure on Sir Lindsay to select Labour’s amendment.

Speaking in the Commons on Thursday morning, she said: “We have seen into the heart of Labour’s leadership. Nothing is more important than the interests of the Labour Party. The Labour Party before principle.

“The Labour Party before individual rights. The Labour Party before the reputation and honour of the decent man that sits in the Speaker’s chair. The Labour Party before fairness, integrity and democracy.”

A Labour MP could then be heard shouting “absolute nonsense” as Ms Mordaunt continued: “He puts the interests of the Labour Party before the interests of the British people. It is the Labour leader that doesn’t get Britain and the past week has shown that he is not fit to lead it.”

Addressing Lucy Powell, the shadow Commons leader, she said: “Firstly, it fell to the Government benches to defend the rights of a minority party in this House.

“If the honourable lady opposite cannot bring herself to reflect on the appalling consequences of her party’s actions yesterday, if she cannot rise above the narrow and immediate needs of her weak and fickle leader, to fulfil her duties to this House as its shadow leader, perhaps she might like to reflect on the damage her party has done to the Office of the Speaker.

“I would never have done to him what the Labour Party have done to him.”

Sir Lindsay’s allies said he picked the Labour amendment because of concerns about MPs’ security and a genuinely held belief that all parties should have their positions put to votes.

But Ms Mordaunt said: “If we are adapting the procedures of this House because we are fearful of the consequences of standing up and saying what we think is right then democracy has failed and the extremists have won. We must never do that.”