In a letter posted on Twitter, the deputy prime minister and justice secretary revealed a report into his behaviour upheld two claims against him.

But he took issue with the findings, calling them "flawed" and claiming they "set a dangerous precedent for the conduct of good government".

Politics live: Raab 'keeps word' and quits

The news comes after Rishi Sunak was presented with an official report into Mr Raab's behaviour on Thursday.

In an article published in the Telegraph shortly after his ousting, the outgoing minister confirmed there had been a total of 15 allegations investigated - but describe the probe as "a Kafkaesque saga".

In a letter responding to the decision, Mr Sunak said he accepted his deputy's resignation "with great sadness", saying it "should not make us forget your record of delivery in both this government and previous administrations".

And the PM said there had been "shortcomings in the historic process that have negatively affected everyone involved", adding: "We should learn from this how to better handle such matters in future".

But Labour leader Sir Keir Starmer said the situation showed "the continual weakness of the prime minister", adding: "He should never have appointed [Mr Raab] in the first place… and then he didn't sack him.

"It is that decision and that weakness I think that goes to the heart, not just of this prime minister, but of the 13 years now of [Conservative] failure and it is why people desperately want a change."

Meanwhile, the Liberal Democrats called for Mr Raab to resign as an MP and for a by-election to be held in his seat, saying he had shown "he is not only unfit to serve as a minister, but is totally unfit to represent his constituents in parliament".

In the letter addressed to the prime minister, Mr Raab wrote: "I called for the inquiry and undertook to resign, if it made any finding of bullying whatsoever. I believe it is important to keep my word."

He said the report - carried out by independent investigator Adam Tolley KC - showed he had "not once, in four and a half years, sworn or shouted at anyone, let alone thrown anything or otherwise physically intimidated anyone, nor intentionally sought to belittle anyone".

But he also attacked the findings, saying the inquiry had set "the threshold for bullying so low" that it had "set a dangerous precedent".

Mr Raab added: "I am genuinely sorry for any unintended stress or offence that any officials felt, as a result of the pace, standards and challenge that I brought to the Ministry of Justice.

"That is, however, what the public expect of ministers working on their behalf."

In his newspaper article, Mr Raab gave more detail about the complaints made against him, saying some staff "complained that I asked too many questions, including in budget meetings with hundreds of millions of pounds of taxpayers' money at stake, curtailed unwieldy interventions in meetings, or that they were intimidated or offended by my body language.

"These were dismissed."

On the allegations that were upheld, he said the report concluded "I had abused my power by replacing a lead negotiator when I was foreign secretary, and as justice secretary had left senior officials feeling insulted on three occasions because of direct feedback".

But he doubled-down on his attack on the process, saying "normal rules of evidence and procedural fairness were disapplied", including a rule for all complaints to be made within three months.

"In my case, all the complaints were stored up for over three months, most over eight months, some for over four years - and then submitted in a coordinated way," he claimed.

"And I was subject to trial by media for six months, fuelled by warped and fabricated accounts leaked by anonymous officials."

Labour's Sir Keir accused Mr Raab of "whining" when the public wanted to hear about things that mattered to them.

"There is a bigger picture here," he said. "We have got a cost of living crisis, there is the future of the NHS that is really, really important… and we are mired in talking about the weaknesses and the inability of the government to actually deliver anything for the people of this country.

"I don't know why Dominic Raab thinks in the middle of a cost of living crisis that anybody wants to hear about his whining about having to resign.

"What I think everybody wants is strong leadership and that has been palpably absent here.

"Why on earth was Raab appointed in the first place? Why on earth didn't the prime minister act more quickly? Why on earth isn't the government laser focuses on the cost of living crisis and the absolute mess of the NHS that they have made?"

The civil service union, the FDA, called for an independent inquiry into ministerial bullying following the findings of the report.

General secretary Dave Penman said: "This resignation is not a vindication of the current system, it's a damning indictment of the inadequacy of a process that relies solely on the prime minister of the day to enforce standards."

Mike Clancy, the boss of another civil service union Prospect, also said there had been "a toxic culture at the top of government for too long with civil servants and public trust paying the price for this chaos", calling on Mr Sunak to now "clean out the rest of the stables".

He added: "These issues go to the heart of the anger and distrust many people feel towards the way our country runs. It is time for ministers to step up and to start restoring trust both for civil servants and the good of the country."

Mr Raab was appointed by Mr Sunak after he took power in October, and less than 48 hours ago was sat alongside the PM at Prime Minister's Questions.

Allegations surfaced about Mr Raab back in November, with former staff claiming he created a "culture of fear" in their departments.

He denied the allegations and requested an investigation into himself after two formal complaints were made.

As the weeks rolled on, more accusations came to light, with one report suggesting as many as 24 complaints had been made.

Mr Sunak has come under pressure over what he knew about Mr Raab's alleged conduct, with a source telling political editor Beth Rigby the PM was informed about Mr Raab's "unacceptable behaviour" before appointing him as his deputy and justice secretary.

Downing Street said Mr Sunak was "not aware" of any "formal complaints" about Mr Raab when he appointed him, but Number 10 did not deny concerns had been expressed informally.

Labour leader Sir Keir Starmer has previously accused the PM of ignoring reports about Mr Raab's conduct.

Mr Raab's departure follows Mr Sunak's decision to dismiss Tory party chairman Nadhim Zahawi from his post in January after the former chancellor was found to have broken the ministerial code over his tax affairs.