LONDON — Gavin Williamson, the U.K. defense chief fired for leaking security information, has denied any involvement in the leak from a secret government meeting about the Chinese telecommunications firm Huawei.

In a letter posted on his Twitter account, Williamson says he was confident that a formal and thorough inquiry would vindicate him. He says he appreciated being offered a chance to resign but "to resign would have been to accept that I, my civil servants, my military advisers or my staff were responsible: this was not the case."

Earlier Wednesday, British Prime Minister Theresa May said in a letter to Williamson that she “can no longer have full confidence” in the defense minister in the wake of the investigation. In the letter released by her office, May told Williamson that there was “compelling evidence” suggesting his “responsibility for the unauthorized disclosure” from the National Security Council.

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 British 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.