Under-fire Sir Gavin Williamson is facing a new probe into expletive-filled texts sent to a Tory colleague.
Work and Pensions Secretary Mel Stride said there was an "independent" inquiry into Sir Gavin's sweary WhatsApp messages to ex-Chief Whip Wendy Morton amid reports the matter has been escalated to Parliament's watchdog.
Ms Morton complained to the Conservative Party about the exchange, where he moaned about not getting a seat at the Queen's funeral. Party chiefs have not confirmed whether a probe has been launched.
She has also reported the matter to the Independent Complaints and Grievances Scheme, which investigates the most serious cases, according to The Times.
Rishi Sunak is under pressure to sack Sir Gavin, who was given a Cabinet Office job even though Mr Sunak knew there was an outstanding complaint against him.
Sir Gavin now faces fresh allegations that he told a senior civil servant to "slit your throat" in front of colleagues during a meeting when he was Defence Secretary.
On another occasion he allegedly told the official to "jump out of the window", according to The Guardian.
Sir Gavin "strongly" rejects the claim and said no specific complaints had ever been brought to his attention.
He could still be in Cabinet by Christmas as the probe into abusive texts to a Tory colleague may take months.
Mr Stride told Sky News: "There is an independent inquiry, as you know, going on around another ... alleged incident between himself and the then-chief whip Wendy Morton.
"I think the important thing we do now is not to start intervening ... and opining on who's right and wrong or what may or may not have happened, but to wait for the results of that investigation.
"And then when we have that, and any other investigation that may be triggered in the meantime, then I think we can take stock and come to a firm conclusion."
He suggested Sir Gavin will still be in post by Christmas as any process "will take some time and we've got to wait to see what comes out of that".
Mr Stride said that no minister was "un-sackable" but spoke of an "aura or mystique around" Sir Gavin.
"The reality with Cronus is he was much touted but he never actually was released to bite anybody," Mr Stride told Sky News, in reference to the pet tarantula owned by Sir Gavin while he was chief whip.
Rishi Sunak’s official spokesman said he had “full confidence” in Sir Gavin, who had attended this morning’s Cabinet meeting.
That is despite No10 admitting claims Mr Williamson told a civil servant to “slit your throat” were “serious allegations”.
The PM's spokesman said: “I’m not aware of any formal complaints currently about his conduct, but we are checking due process before commenting further.”
Labour Party chair Anneliese Dodds said: "The lack of faith in the Conservative Party complaints process shows how rotten the culture at the heart of this party goes - and the buck stops with Rishi Sunak.
"He was warned about Gavin Williamson’s behaviour and appointed him anyway. He has done grubby deal after grubby deal to become Prime Minister and now must take responsibility and stop putting party management before national interest."
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."
A Conservative spokesman: “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.”
The ICGS does not confirm whether probes are taking place to protect confidentiality of all parties.
