London (CNN) British Prime Minister Theresa May has fired her Defense Secretary Gavin Williamson over the leaking of a key decision related to the Chinese telecoms company Huawei from a UK National Security Council meeting.

May's surprise decision followed an inquiry into how the Daily Telegraph newspaper discovered that the UK government was preparing to give Huawei access to parts of the country's 5G mobile network.

"The Prime Minister has this evening asked Gavin Williamson to leave the Government, having lost confidence in his ability to serve his role of Defence Secretary and as a member of her Cabinet," the statement said.

"The Prime Minister's decision has been informed by his conduct surrounding an investigation into the circumstances of the unauthorized disclosure of information from a meeting of the UK National Security Council."

Williamson "strenuously" denied he was the source of the leak, in a letter posted to his Twitter account on Wednesday night.

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