London (AFP) - British Prime Minister Theresa May on Wednesday sacked Defence Secretary Gavin Williamson following a probe into the leak of news that Britain had conditionally allowed China's Huawei to develop its 5G network.
"The Prime Minister has this evening asked Gavin Williamson to leave the government, having lost confidence in his ability to serve in the role of Defence Secretary and as a member of her Cabinet," said a spokeswoman from her Downing Street office.
May said in a letter to Williamson that the investigation "provides compelling evidence suggesting your responsibility for the unauthorised disclosure" from the April 23 meeting of the National Security Council (NSC), although he "strenuously denied" responsibility.
"No other credible version of events to explain this leak has been identified," wrote May.
"This is an extremely serious matter and a deeply disappointing one," she added, with Williamson now facing the possibility of a criminal probe.
"This must now be referred to the Metropolitan Police for a thorough criminal investigation into breaches of the Official Secrets Act," said Liberal Democrat Leader Vince Cable.
Williamson responded in a letter to May, saying he was "sorry you felt recent leaks" originated from the defence ministry.
"I strenuously deny that I was in any way involved in this leak and I am confident that a thorough and formal inquiry would have vindicated my position".
He revealed that May had given him the chance to resign, but turned it down as it would have been an acceptance of guilt.
Downing Street later announced that Penny Mordaunt, the Minister for Women and Equalities, would replace Williamson and become Britain's first female defence minister, while continuing in her current role.
Britain's already splintered government was rocked by the scandal last month over who leaked news that May was to let Huawei develop Britain's 5G network.
The bitterly disputed decision was reportedly made at the April 23 meeting of the NSC.
NSC discussions are only attended by senior ministers and security officials who first sign the Official Secrets Act that commits them to keep conversations private or risk prosecution.
But The Daily Telegraph newspaper reported that May approved granting Huawei permission to build up "non-core" elements of Britain's next-generation telecommunications network.
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The United States is adamantly opposed to Huawei's involvement because of the firm's obligation under Chinese law to help its home government gather intelligence or provide other security services when required.
May told Williamson it was "vital" that members of the NSC... were able to have "frank and detailed discussions in full confidence" that they would not be made public.
She added that she was "concerned by the manner in which you have engaged with this investigation", saying his conduct "has not been of the same standard" as other members of the NSC.
British media reported that Cabinet Secretary Mark Sedwill -- the country's most senior civil servant -- gave those present an ultimatum to deny responsibility for the leak.
Williamson was one of the first to do so, calling it "completely unacceptable".
His allies told Sky News reporter Kate McCann that they suspect Sedwill of engineering the sacking over historical disagreements between the pair.
The 42-year-old was a trusted ally of the prime minister.
He was May's parliamentary campaign manager when she successfully ran to become Conservative Party leader, and was rewarded with the job of chief whip -- tasked with enforcing discipline for the Conservative Party in parliament.
He was only elected to parliament in 2010, and was best known for keeping a pet tarantula, Cronus, in a glass-sided tank on his desk.
May raised eyebrows when she appointed Williamson to the key defence job in November 2017 after previous incumbent Michael Fallon resigned over allegations of sexual harassment.
The move raised questions about whether Williamson's whips' office had a role in preparing the dossier on ministers behind the scandal, and there were reports that Williamson advised May that Fallon may be facing further allegations.
"Make no mistake, Gavin Williamson wants to be prime minister. And he knows all the dirt on his colleagues," wrote Tim Shipman, political editor of The Sunday Times newspaper.