Rishi Sunak believes Sir Gavin Williamson’s account of events on the allegations he is facing and still has confidence in the cabinet minister, Downing Street has said.

The Guardian newspaper reported that Sir Gavin allegedly told a senior civil servant to “slit your throat” while he was defence secretary.

An ex-official from the Ministry of Defence told the newspaper that Sir Gavin also told them to “jump out of the window”, in what they felt was a sustained campaign of bullying.

According to The Guardian, the civil servant, who later left government, said Sir Gavin “deliberately demeaned and intimidated” them on a regular basis.

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But in a statement, Sir Gavin said: “I strongly reject this allegation and have enjoyed good working relationships with the many brilliant officials I have worked with across government.

“No specific allegations have ever been brought to my attention.”

Downing Street described the latest allegations as “serious” and said it would consider “proper processes” before commenting further.

The prime minister’s official spokesman said: “Obviously, there have been further allegations reported this morning. Those are serious allegations that have come in. It’s true that no formal complaint has been made.”

The spokesman also confirmed that Sir Gavin attended a meeting of Mr Sunak’s cabinet earlier today.

While the senior civil servant who made the allegations is said to have reported the incidents informally to the MoD’s head of human resources, they decided against making a formal complaint.

However, they said a senior military aide working in the department later apologised to them for not calling out his behaviour.

A Cabinet Office spokesman said: “The Cabinet Office has not received notice of any formal complaints about Gavin Williamson’s behaviour from his time at the Ministry of Defence or any other department.”

Work and Pensions Secretary Mel Stride told Sky News earlier today that it would be “utterly, utterly unacceptable” if Sir Gavin made the alleged remarks.

“If that is the case, that is utterly, utterly unacceptable, but at the moment it is in the realm of media speculation,” he said.

Mr Stride said he served in the Whips’ Office under Sir Gavin, and saw him as someone with “this sort of aura or mystique around him”.

“There was always this great aura of… do you remember Cronus, the spider, the tarantula etc? And the reality with Cronus is he was much touted but he never actually was released to bite anybody,” he told Kay Burley.

“So that was how I always saw Gavin – as somebody who had this sort of aura or mystique around him, but the reality was he just generally got on with his job.”

Mr Stride said he is “not going to speculate on anybody’s future”, but when probed on whether he believes Sir Gavin will still be a Cabinet Office minister by Christmas, added: “I suspect the answer to that is yes.”

Meanwhile, earlier this morning, it was confirmed that former chief whip Wendy Morton has referred another allegation made against Sir Gavin – that he sent “abusive” messages to her – for an independent investigation by a parliamentary watchdog.

The Cabinet Office minister was already facing an internal Conservative Party investigation over the series of threatening messages reportedly send to Ms Morton complaining he had been excluded from the Queen’s funeral.

But now the Independent Complaints and Grievance Scheme will also look at the allegations.

Sir Gavin, a backbencher at the time the messages were allegedly sent, accused Ms Morton of using the death of the monarch to “punish” senior MPs who were out of favour with Liz Truss’s government.

The messages, which were originally obtained by The Sunday Times, concluded with Sir Gavin saying: “Well let’s see how many more times you **** us all over. There is a price for everything.”

Former Conservative Party chairman Jake Berry has claimed he told Prime Minister Rishi Sunak that Ms Morton had submitted a formal complaint about Sir Gavin’s conduct the day before he entered Number 10.

On Sunday, Cabinet Office minister Oliver Dowden told Sky News’ Sophy Ridge on Sunday programme that Mr Sunak knew there was a “difficult relationship” between Sir Gavin and Ms Morton, but “wasn’t aware” of “specific allegations”.

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Responding to Ms Morton having referred her complaint against Sir Gavin to Parliament’s Independent Complaints and Grievance Scheme, Chair of the Labour Party, Anneliese Dodds, said Mr Sunak “must take responsibility and stop putting party management before national interest”.

Speaking to reporters as he arrived at a cabinet meeting in Downing Street on Tuesday morning, Business Secretary Grant Shapps said Sir Gavin had apologised for sending abusive messages to a colleague.

A Tory spokesperson said: “The Conservative Party has a robust complaints process in place. This process is rightly a confidential one, so that complainants can come forward in confidence.”

Sir Gavin served as defence secretary from November 2017 until May 2019, but was fired by then-PM Theresa May over a row around a leak from government.

He was hired back by Boris Johnson as education secretary two months later, but was again ousted in September 2021 after much criticism of his handling of the brief during the COVID pandemic.

Mr Sunak brought him back into government two weeks ago to serve as a Cabinet Office minister who also attends cabinet.