LONDON — British Defense Secretary Gavin Williamson was summarily fired Wednesday after an investigation into leaks from a secret government meeting about Chinese telecoms firm Huawei.

In a letter to Williamson, Prime Minister Theresa May said she "can no longer have full confidence" in Williamson in the wake of the investigation.

In the letter released by Downing St., May told Williamson that there was "compelling evidence" suggesting his "responsibility for the unauthorized disclosure" from the National Security Council.

"No other, credible version of events to explain this leak has been identified," she said.

There was no immediate comment from Williamson.

Penny Mordaunt, the international development secretary, has been appointed as Williamson's replacement. She becomes the first woman to hold the post.

An investigation was launched last week after newspapers reported that the security council, which meets in private, had agreed to let Huawei participate in some aspects of Britain's new 5G wireless communications network.

The government insists no decision has been made about Huawei.

The United States has been lobbying allies to exclude Huawei from all 5G networks, noting that the Chinese government can force the company to give it backdoor access to data on its networks.

The security council includes senior ministers, who receive briefings from top military and intelligence officials, and its meetings are considered highly sensitive.

The leak comes amid a Brexit-fueled breakdown in government discipline. With May weakened by her failure to take Britain out of the European Union, multiple ministers are positioning themselves to try to replace her, partly by cultivating positive press coverage.

The Daily Telegraph said last week it had obtained details of security council meetings about Huawei. It said several ministers, including Williamson, had opposed letting Huawei work on Britain's 5G network.