Three sailors aboard a Royal Navy submarine carrying 16 nuclear missiles have been caught taking cocaine, The Mail on Sunday can exclusively reveal.

The submariners from HMS Vengeance failed a Compulsory Drugs Test (CDT) for the Class-A substance shortly after the 15,900-ton vessel visited a US military port in Florida.

Their urine samples were examined while the submarine continued its top-secret operations and the three crew members were removed from HMS Vengeance when she returned to Her Majesty’s Naval Base Clyde at Faslane, Scotland.

Three sailors on nuclear-armed Royal Navy submarine have been caught taking cocaine

Last night, military sources suggested the three sailors were part of a larger group of HMS Vengeance crew members who took cocaine during a recent ‘run ashore’.

Those others sailors are understood to have passed CDT tests after drinking copious amounts of water to flush the drug out of their bodies. The Royal Navy has declined to comment on this claim.

The cocaine scandal aboard HMS Vengeance comes just two months after The Mail on Sunday revealed how seven sailors had been kicked off another Royal Navy submarine after taking the same drug. They were marched off HMS Talent after testing positive while on duty.

But military sources say cocaine use among crew members of HMS Vengeance is a bigger blow for the Royal Navy because the 150m-long vessel carries Trident nuclear missiles, which can kill millions when fully armed and have a range of 7,500 miles.

Their destructive power has been estimated as the equivalent of eight times the atomic blast that flattened the Japanese city Hiroshima in the Second World War.

They failed a compulsory drugs test when they pulled into a port in Florida. The vessel was carrying 16 nuclear missiles

HMS Vengeance is the youngest of the Royal Navy’s Vanguard class submarines and entered service in 2001.

It also carries the sealed letters of last resort – instructions from the Prime Minister to be followed in the aftermath of a national catastrophe or a nuclear strike.

Three years ago, a test-firing of a £17 million Trident II D5 missile from HMS Vengeance went badly wrong, forcing submarine officers to over-ride its guidance system and force it to crash harmlessly into the sea off the coast of Florida. Downing Street was later accused of attempting to cover up the incident.

The missiles aboard HMS Vengeance can travel at 13,600mph. At the time of the test, commercial airlines received warnings to steer clear of its flight path.

Typically, HMS Vengeance sails with a crew of 121 ratings and 14 officers. The Royal Navy declined to provide the ranks of those who failed the CDTs but they are understood to be from lower ranks.

The Royal Navy has always maintained a literal interpretation of the Ministry of Defence’s ‘zero tolerance’ policy towards drug taking.

Only if sailors can prove they were unaware that they consumed a banned substance – such as when their drink is spiked – do commanders grant a reprieve.

Last year, former Defence Secretary Gavin Williamson responded to a series of exposés in The Mail on Sunday about drug-taking in the Army by ordering regimental commanders to stop giving young soldiers caught taking cocaine and other substances second chances.

We also revealed that some repeat offenders had even received third chances because senior officers feared their regiments were already so under-manned.

Last night, the Royal Navy said: ‘The Ministry of Defence has a zero-tolerance drugs policy and will not tolerate misuse of drugs by service personnel in any form or at any time.

‘Any personnel caught taking drugs will be discharged.’