LONDON - A second fortuitous discovery of a designer steroid manufactured specifically to fool the dope-testers has confirmed the worst fears of the anti-doping authorities.

After several elite track athletes were banned for using THG (tetrahydrogestrinone), scientists have discovered another previously undetectable substance called DMT (desoxy-methyl-testosterone).

The announcement yesterday by World Anti-Doping Agency scientific director Olivier Rabin serves only to endorse the boast of Victor Conte, head of the Balco laboratory, which federal investigators believe manufactured and distributed THG.

"You think it's over just because they've indicted me? Please. There's a new version out there right now," Conte said last year.

It is not known whether Conte, who is expected to go on trial next month, was referring to DMT.

As Don Catlin, head of the Olympic Analytical Laboratory, which developed a test for THG, said last year: "The number of totally unknown designer drugs has just come of age because of Balco."

THG was discovered in 2003 after the US Anti-Doping Agency received a tipoff from leading track coach Trevor Graham.

Graham, who did not reveal his identity until the Athens Olympics last August, then sent a syringe of THG to the agency. Catlin's scientists determined that it was related to the banned drug gestrinone.

After federal investigators raided Balco, the US governing athletics body said American shotput champion Kevin Toth, women's hammer champion Melissa Price, men's hammer thrower John McEwen and middle-distance runner Regina Jacobs had tested positive for THG.

Jacobs retired and the other athletes were banned for two years.

The two most prominent athletes to be suspended for taking THG have been double world sprint champion Kelli White and Britain's European 100m champion, Dwain Chambers.

White was suspended for two years after admitting to taking a variety of drugs including THG, while Chambers received the same suspension after a positive test.

There are certain to be further casualties of the scandal this year.

Tim Montgomery, the world 100m champion, has been charged with serious doping offences and his partner, Marion Jones, a triple gold medallist at the 2000 Sydney Olympics, has also been investigated.

Conte claimed to have supplied both with drugs, including THG. Jones, who has not been charged, has denied the allegations and said she would sue Conte for defamation.

DMT is several generations ahead of THG, essentially a modification of a drug already in use.

"Whoever made this drug had access to serious organic chemists," said Christiane Ayotte, head of the Montreal laboratory that identified the substance. "It is at a level of sophistication that we have not seen before."