A Trident nuclear missile misfired and crashed into the ocean near the submarine that launched it during a test last month, it has been reported.

It is the second misfire in a row, after a failed launch in 2016.

The missile’s first stage boosters did not ignite during a test launch by HMS Vanguard on January 30, and it fell into the ocean and sank, the Sun reported.

The Ministry of Defence confirmed that an “anomaly” occurred during the test off the coast of Florida but refused to provide further information on the grounds of national security.

Defence Secretary Grant Shapps and First Sea Lord Admiral Sir Ben Key were both on board the submarine during the test, according to the newspaper.

An investigation began into what went wrong, and a search was ordered to recover the top-secret technology from the seabed, it was reported.

The test, which involved a dummy warhead, was the last before the £4 billion submarine re-enters service after a seven-year refit in Plymouth.

The Ministry of Defence said all tests had been passed and insisted that it has “absolute confidence” in the nuclear deterrent.  

A submarine carrying nuclear weapons has been on patrol at all times since 1969 as part of the UK’s continuous at sea deterrent.

The Royal Navy has four Vanguard class vessels which fulfil this role on rotation. They carry around 140 crew, as well as Trident ballistic missiles.

The ageing vessels, which have been in service for 30 years, are set to be replaced in the 2030s by the Dreadnought class, which are currently under construction.

In November, a Vanguard class submarine was reported to have had a near miss after a gauge malfunctioned and left it sinking towards an unsafe depth.

An MOD Spokesperson said: “HMS Vanguard and her crew have been proven fully capable of operating the UK’s Continuous At-Sea Deterrent, passing all tests during a recent demonstration and shakedown operation (DASO) - a routine test to confirm that the submarine can return to service following deep maintenance work.

“The test has reaffirmed the effectiveness of the UK’s nuclear deterrent, in which we have absolute confidence.

“During the test an anomaly occurred. As a matter of national security, we cannot provide further information on this, however we are confident that the anomaly was event specific, and therefore there are no implications for the reliability of the wider Trident missile systems and stockpile. The UK’s nuclear deterrent remains safe, secure and effective.”