Scientists say they have made a dramatic breakthrough in the battle against performance-enhancing drugs.

BBC Correspondent Adam Mynott in Lausanne: Dramatic breakthrough

The BBC has learned that researchers at St Thomas' Hospital in London have, for the first time, found a way of detecting human growth hormone, a drug which helps athletes put on muscle.

The man who has led the research funded by the International Olympic Committee, Professor Peter Sonksen, described it as a major breakthrough.

Professor Peter Sonksen: "What we thought was uncrackable has been cracked"

"Three years ago, we were optimistic to do something. I think we've exceeded our wildest dreams", he said.

"We've got a test which is more sensitive, more specific than we ever imaged."

A research programme has been under way for the past three years, trying to find a means of identifying athletes who have been injecting themselves with human growth hormone, HGH.

Difficult to detect HGH

HGH has a similar affect to steroids, allowing cheating competitors to put on extra muscle bulk.

The problem for the doping control authorities has been detecting its administration because HGH is a naturally occurring substance in the body.

There are still some legal and administrative hurdles to cross before the HGH test is fully operational.

But Professor Sonksen sees no reason why it should not be ready in time for the Olympic Games in Sydney.

"I think that if we can get this test up and running in Sydney in the year 2000, there will be a tremendous amount of interest and support both from the athletes as well as sports administrators", he said.

The test will require athletes to give a tiny amount of blood - just a pinprick.

But many athletes have been calling for blood testing to help catch cheats and this latest development will be welcomed as another victory in the battle against drug abuse.