The initiative comes after a successful experiment in Jamaica that resulted in a significant fall in the number of people smuggling drugs into Britain inside their bodies.

Equipment is being sent to Antigua, St Lucia, Grenada, Trinidad, Tobago, Barbados, Grand Cayman and Grand Turk to prevent them becoming new drug transit zones.

After highly sensitive scanners were installed at Jamaican airports, the number of drug mules caught before boarding flights doubled, while arrests in Britain fell by 75 per cent.

Now officials fear that the drug gangs — an alliance of Colombian cartels who produce the cocaine, and Jamaican Yardies who smuggle it to British cities — will seek new ground.

Other islands have swiftly accepted the offer from the Foreign and Commonwealth Office to provide the scanning equipment, with training from customs officers.

The scanners, produced by the American security specialists GE Ion Track, are sensitive enough to detect traces of cocaine powder on skin and clothes.

British officials moved to stem the flow of drugs from the Caribbean after 25 passengers were caught smuggling cocaine on an Air Jamaica flight into Heathrow on December 3, 2001. They had swallowed £1.5 million of the drug and one woman allegedly had 94 thumb-sized packages of cocaine inside her. Remarkably, the mules did not seem to know each other.

It was the peak of a drug-smuggling trade that had embarrassed Jamaica, with British diplomats going on the record to say at least one in ten passengers from the island was a drug mule.

The scam regularly killed smugglers when bags of cocaine burst inside them. Nearly a tenth of the cocaine smuggled into Britain comes from Jamaica and around half was smuggled by mules.

Drug mules are able to conceal up to a kilogram of cocaine. Some strap packets of the drug to their skin, hidden under clothing. The rest are divided into “swallowers” and “stuffers”.

The swallowers fill their stomachs with small packages wrapped in condoms or balloons. They cannot eat or drink until they reach Britain and are given the address of a safe house, where gangsters wait until they pass the drugs through their systems.

Swallowers are often spotted by air stewards whose suspicion is aroused when they refuse meals and drinks during nine-hour flights.

Stuffers hide the cocaine in bodily passages, but risk detection if they are subjected to intimate searches at an airport.

Drug mules are not the most important source of cocaine — sophisticated freight smuggling is the most effective method — but they are infuriatingly time-consuming for customs staff.

Some gangsters are suspected of deliberately planting obvious drug mules as decoys on flights where large consignments are being smuggled in suitcases. Customs officials may be too busy dealing with the mules to catch the main stash of cocaine.

Harry Fletcher, of the National Association of Probation Officers, said: “If you pick somebody who is particularly anxious and sweating, they will be conspicuous. They are sacrifices.”

A successful mule can be used time and again. About 70 per cent of Jamaican mules are men. They are recruited by criminal gangs usually offering £1,000 to £2,000 for a journey, though recent intelligence suggests the price has risen since the chances of detection have soared.

Many mules are fooled by gangsters into thinking that, if they are caught, they will be deported to Jamaica.

In fact, they face a long stretch in prison and, unlike British drug smugglers, have no chance of parole because they have no British addresses.

After the debacle of the December 2001 flight, Britain resolved to work tirelessly with Jamaica to outwit the drug gangs.

In May 2002, the “Airbridge” initiative saw Britain pay for cocaine-detecting machines at Jamaican airports. Sir John Stevens, the Metropolitan Police Commissioner, visited Jamaica last summer to praise what he described as an unprecedented collaboration.

The Jamaican Government sought to outwit the gangs’ propaganda with a lurid poster campaign giving warning that mules would now be detected and faced long prison sentences. In January, Britain finally carried out a longstanding threat to impose visa controls on Jamaicans. Outwardly this was to prevent illegal immigration, but officials knew that the effect would be to deter drug smugglers.

Explore UK News

• Crime News

• Education News

• Health News

• Science News

• Scotland News

Times Recommends

• Revealed: how Eurocrat leaked secrets over dinners
• Politicians use the net to brainstorm
• British spy in longbow plot to kill Himmler