Rishi Sunak is standing by under-fire Sir Gavin Williamson who is accused of sending abusive messages to a Tory colleague complaining about not being invited to the Queen's funeral.
Sir Gavin allegedly accused the then-Chief Whip Wendy Morton of using the death of the Queen to "punish" senior MPs who were out of favour with Liz Truss's Government.
A leaked exchange of expletive-ridden messages concluded with him saying: "Well let's see how many more times you f*** us all over. There is a price for everything."
Sir Gavin, who was sacked from both Boris Johnson and Theresa May's cabinets, was brought back into Government by Rishi Sunak last week.
Former Tory chairman Sir Jake Berry informed Mr Sunak before he entered No10 that Ms Morton had submitted a formal complaint to the party about Sir Gavin’s conduct, according to the Sunday Times.
Cabinet Office Minister Oliver Dowden said the Prime Minister had been informed of a complaint made by Ms Morton but added: "In terms of the specific allegations, the specific exchange, the Prime Minister wasn't aware of it until last night."
He insisted the PM still had confidence in Sir Gavin.
Mr Dowden told Sky News: “These were sent in the heat of the moment - expressing frustration. It was a difficult time for the party.
“He now accepts he shouldn’t have done it and he regrets doing so. I think that is right, and thankfully we're in a better place now."
Asked if the Prime Minister still had confidence in Mr Williamson, he said: "Well he shouldn't have sent those messages and he says he regrets it but of course the Prime Minister continues to have confidence in Gavin Williamson as a minister."
He said Mr Sunak had not seen this exchange of texts until they were published in the media but the PM knew there was "a difficult relationship".
"In terms of these specific allegations, the Prime Minister wasn't aware of that," Mr Dowden said.
But Lib Dem deputy leader Daisy Cooper said: "These shocking revelations raise yet more serious questions about Rishi Sunak's judgement.
"If the Prime Minister was serious about restoring integrity he would sack Gavin Williamson.”
Labour frontbencher Ed Miliband demanded an independent investigation to prevent a "whitewash".
He said: "It really calls into question Rishi Sunak's judgement and the way he made decisions about his Cabinet.
"We already knew about the whole Suella Braverman issue - being appointed six days after she resigned. I think it was very noticeable that Oliver Dowden couldn't deny that Rishi Sunak knew about those issues to with potential bullying against Wendy Morton, the chief whip, by Gavin Williamson and yet he reappointed him.
"What it says is that Rishi Sunak was making decisions simply in his own narrow short term interest for the Conservative Party leadership, not the national interest, and there needs to be an urgent independent investigation into exactly what happened."
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."
