Theresa May has refused to say whether she knew that a Trident missile had misfired just weeks before a Commons vote on the future of the nuclear deterrent.

The Prime Minister declined four times to answer questions about whether she was aware that the launch of an unarmed Trident II D5 missile from a British submarine off the coast of Florida in June malfunctioned.

Downing Street has been accused of covering up the failure, which was reported in the Sunday Times.

Asked repeatedly on the BBC’s Andrew Marr show about whether she personally knew about the misfire, Mrs May said only: “I have absolute faith in our Trident missiles.”

She added: “I think we should defend our country.”