LONDON (Reuters) - A test firing of an unarmed British nuclear Trident missile from a submarine off the coast of Florida malfunctioned last June, the Sunday Times newspaper reported.
The paper quoted an unnamed senior naval source as saying the missile may have veered off in the wrong direction toward the American mainland.
The paper said it was the only test firing of a British nuclear missile in four years and came shortly before Theresa May became Prime Minister last year in the wake of Britain's vote to leave the European Union.
It said May had omitted any mention of the failed test when she persuaded parliament to spend 40 billion pounds on new Trident submarines in her first major speech before parliament last July.
Parliament, which in 2007 agreed in principle to replace the deterrent system, last year voted to approve the building of four submarines to ensure Britain can have nuclear weapons continuously on patrol at sea.
Trident missiles have been test-fired only five times by UK submarines this century because they cost 17 million pounds ($21.03 million) apiece, the paper said.
May's office and Britain's Ministry of Defence said in a joint statement: "In June, the Royal Navy conducted a routine unarmed Trident missile test launch from HMS Vengeance, as part of an operation which is designed to certify the submarine and its crew.
"Vengeance and her crew were successfully tested and certified, allowing Vengeance to return into service. We have absolute confidence in our independent nuclear deterrent.
"We do not provide further details on submarine operations for obvious national security reasons."