Small quantities of gamma hydroxy butyrate (GHB), which is banned in the United States but not an illegal substance in the UK, are already available at nightclubs in London. It has also been reported in the North-west of England.
Costing from pounds 10 to pounds 15 a dose, GHB reportedly induced coma in some users in the US, where it was originally developed. Because it comes as a clear, colourless liquid, it is easy to overdose.
Also known as Liquid X, it was manufactured as an anaesthetic for operations, but went out of use because of unpredictable side-effects. In the Eighties it was used by bodybuilders as a growth- hormone stimulant. It was banned in the US in 1991 because of its psychedelic effects, which include hallucinations and immunity to pain.
More recently, however, it has become popular in the Californian dance scene and its effects have been likened to a combination of Ecstasy and LSD. It also makes users feel drowsy, which has led some to mix it with mind- stimulating amphetamines to prolong the 'high' by several hours.
The drug is not currently on the Home Office's list of prohibited drugs, ones which it is illegal to possess. However, a spokesman said the situation would be reviewed if people were found to be abusing GHB.
Drug agencies fear that youngsters, ever keen to try new narcotics, will quickly take to GHB. Laura Gamble, a spokeswoman for the Brighton-based Drug Advice and Information Service, said: 'Unfortunately, any new drugs fad is quickly seized upon. There are real dangers with GHB - taking something as powerful as this puts a tremendous strain on the body.'
The price of GHB - cheaper than the most popular dance drug, Ecstasy, which costs about pounds 15 a tablet - will add to its attraction.
Dr Russell Newcombe, director of 3D Research Bureau, an independent drugs agency, said: 'High doses of a drug like this can produce a comatose effect. The combination of hallucination and the loss of perception of pain could result in someone battering themselves against a hard object, such as a wall, without realising they are seriously injuring themselves.'
Lifeline, a drugs agency based in Manchester, has had several 'anecdotal' reports of the drug in the North-west.
Last year, small amounts of another anaesthetic drug, Ketamine, or 'Special K', normally used for at-the-scene emergency surgery, began to be sold at clubs and raves.