A new poster campaign is being released throughout the Navy and Royal Marines this month to reiterate the Service’s zero tolerance stance on drug use.

Drug test chiefs say despite the tiny proportion of sailors caught by random checks, the Royal Navy cannot afford to let its guard down.

Home Office figures show that a quarter of all 16 to 29-year-olds in the UK have used illegal drugs in the past 12 months.

Of the 13,803 sailors and Royal Marines checked by the Compulsory Drugs Test (CDT) team in 2003, just 56 – fewer than one in 200 personnel – tested positive.

But the CDT team said there was no room for complacency.

“We want to make sure that all the Royal Navy remains aware that taking drugs is not acceptable,” said a CDT team spokesman.

“We have a zero tolerance policy – illegal drugs are not only bad for health, they also endanger those around a sailor as they can impair decision-making and the ability to function normally.”

Every ship and establishment in the Navy will receive the new posters, which feature dramatic, eye-catching images such as a Sea Harrier flying straight up, along with simple messages.

The campaign comes in the wake of the re-classification of cannabis by the Government.

Despite this change, the Royal Navy’s stance towards cannabis remains unequivocal: its use is illegal.

Since compulsory random tests were introduced in 1997, more than 91,000 sailors have been checked.

A four-strong team visits RN personnel all over the world, from Iraq to the Falklands, from shore bases to submarines, and it arrives without warning.

Despite the admonitions – a positive test almost certainly leads to a dishonourable discharge – the carrot is also being applied as well as the stick, with drug education courses every two years for officers and ranks.