The British government covered up a failed test of a nuclear missile system last year, just weeks before lawmakers voted to renew it, "The Sunday Times" newspaper alleged on Sunday.

The newspaper cited an anonymous senior naval source who claimed that the unarmed Trident II D5 missile failed after being launched from a British submarine off the coast of the US state of Florida in June.

The cause of the failure was top secret, but the source said the missile may have accidentally veered towards the mainland.

"There was a major panic at the highest level of government and the military after the first test of our nuclear deterrent in four years ended in disastrous failure," the source told the paper.

"Ultimately, Downing Street decided to cover up the failed test. If the information was made public, they knew how damaging it would be to the credibility of our nuclear deterrent."

The source said an upcoming parliamentary vote on the Trident system on July 18 had made the failure "all the more sensitive."

'Absolute faith in Trident missiles'

In a BBC interview on Sunday, Prime Minister Theresa May did not say whether she knew about the malfunction when she successfully urged the House of Commons to support updating the aging submarines that carry Britain's nuclear arsenal at a cost of 41 billion pounds (47 billion euros).

May was not prime minister during the test, but took office shortly before the vote. In the parliamentary debate she called for the renewal to deter "serious threats," warning of "a continuing risk of further proliferation of nuclear weapons."

After more than five hours of debate, parliament approved a 2007 decision to build four new submarines to ensure Britain could have nuclear weapons continuously on patrol at sea.

Many Britons are opposed to Trident

But more than 100 of parliament's 650 members voted against the decision, arguing the weapons were no longer needed as they were unhelpful against terrorists and the money could be better spent elsewhere.

"What we were talking about is whether or not we should renew Trident," May said in the BBC interview.

"I have absolute faith in our Trident missiles," she continued, adding that tests take place "regularly".

Five tests since 2000

According to "The Times," Britain has conducted only five tests of Trident missiles from submarines since 2000, partly due to the 17 million pound cost of each launch.

Opposition Labour leader Jeremy Corbyn, a strident critic of nuclear weapons, said it was a "pretty catastrophic error" for a missile to go in the wrong direction.

A government spokesman confirmed that the Royal Navy had conducted a routine test-launch of an unarmed missile in June from HMS Vengeance, one of the country's four nuclear-armed submarines.

It was "part of an operation which is designed to certify the submarine and its crew," he said.

"Vengeance and her crew were successfully tested and certified, allowing Vengeance to return into service. We have absolute confidence in our independent nuclear deterrent," he said.

aw/tj (AFP, dpa)