Gavin Williamson: Downing Street looking into bullying claims
Downing Street has said it is seeking to establish the facts about abusive comments allegedly made by Cabinet Office minister Sir Gavin Williamson.
A senior civil servant told the Guardian Sir Gavin had bullied them and told them to "slit your throat".
He has also been reported to the MPs' bullying watchdog over messages to Tory colleague Wendy Morton.
Sir Gavin denies the allegations. No 10 said it was looking into the claims and was prepared to take action.
Prime Minister Rishi Sunak has said the language Sir Gavin had used was "not acceptable", but No 10 earlier insisted the PM still has full confidence in him.
A series of text messages by Sir Gavin to Tory colleague and then-Chief Whip Wendy Morton were published on Sunday.
In them, he appears to complain MPs not "favoured" by then-Prime Minister Liz Truss were being excluded from attending the Queen's funeral at Westminster Abbey.
He accused Ms Morton of "rigging" the ticket allocation to punish people - including himself - who were not supportive enough of Ms Truss.
Sir Gavin reportedly warned Ms Morton "not to push him about" and that "there is a price for everything".
Last month, Ms Morton sent the messages to the Conservative Party after making a formal complaint about Sir Gavin's behaviour.
On Tuesday, she referred Sir Gavin to Parliament's Independent Complaints and Grievance Scheme (ICGS). 
ks into claims of parliamentarians and staff who feel they have been bullied or harassed. 
Guardian has reported that the senior civil servant who claims to have been bullied by Sir Gavin has also referred the MP to the ICGS.
Last year, investigations by the ICGS took 216 days on average to complete.
Under the process, complaints are initially assessed by an external investigator. A decision is then made on whether to move to a full investigation.
Downing Street said it was carrying out an informal fact-finding investigation into the comments as well.
rime minister's spokesman said the investigation may act before either of the existing processes are complete.
Meanwhile, Sir Gavin's former deputy when he was chief whip claimed he acted in an "unethical and immoral" way in the role. 
Anne Milton, who was deputy chief whip from May 2015 to July 2017, described his behaviour as "threatening" and "intimidating". 
Ms Milton, who was expelled from the Conservative parliamentary party in 2019 over Brexit and subsequently lost her seat, told Channel 4 News: "I got the impression that he loved salacious gossip, and would use it as leverage against MPs if the need arose."
Watch: Sunak on Williamson texts - Not right, not acceptable
In response to the allegations by Ms Morton, Sir Gavin told the Sunday Times: "I of course regret getting frustrated about the way colleagues and I felt we were being treated."
Asked if it amounted to bullying, Mr Sunak said "an independent complaints process" was under way and it would be "right to let that process conclude".
In a separate development, an unnamed Ministry of Defence official told the Guardian Sir Gavin told them to "slit your throat" and "jump out of the window" when he was defence secretary. 
fficial said they raised concerns to the Ministry of Defence's human resources department but made no formal complaint.
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."
Mr Williamson does not deny using the language.
Sir Gavin was defence secretary between 2017 and 2019 under Theresa May, until he was forced to resign after details of Huawei's potential involvement in the UK's 5G network were leaked.
He was brought back into government by Mr Sunak, after helping run the prime minister's leadership campaign.
Labour frontbencher Jonathan Ashworth said Rishi Sunak had shown a "complete lack of judgement" in bringing Sir Gavin back into government despite knowing there were allegations against him.
He said Mr Williamson portrayed himself as a "cartoonish character bullying colleagues" and that "it's just not what we need around the cabinet table".
Sir Gavin was appointed minister without portfolio on the first day of Mr Sunak's premiership. Among his responsibilities are tackling overseas conflict and improving the government's communications. 
Work and Pensions Secretary Mel Stride said Sir Gavin's role in government was "very important".
Mr Stride told Times Radio: "I think Gavin is somebody who, as I say, has particular talents and a particular understanding of the parliamentary party."
Liberal Democrats are demanding an independent Cabinet Office inquiry into Sir Gavin's remarks.
"Anything less would be an abdication of leadership from Number 10, and make a mockery of Sunak's promise to govern with integrity," Lib Dem spokesperson Christine Jardine said.