LONDON -- British sprinter Dwain Chambers' backup urine sample confirmed a positive test for the steroid THG, The Associated Press learned Thursday.

Chambers, the European 100-meter champion, now faces the possibility of a ban lasting two years or longer, which would mean missing the Athens Olympics. He is one of five track and field athletes who tested positive for the recently discovered drug.

Chambers' lawyer confirmed Oct. 22 that an out-of-competition test in Germany in August came back positive for THG, or tetrahydrogestrinone.

A backup sample was analyzed Monday at the UCLA doping control laboratory in California and came back positive, according to a track official with direct knowledge of the result who spoke on condition of anonymity.

Both samples must be positive before an athlete is officially charged with a doping offense.

The sport's world governing body, the International Association of Athletics Federations, said it could not comment Thursday.

UK Athletics said it was waiting for notification from the IAAF. Chambers' lawyer, Graham Shear, said, "I've heard absolutely nothing."

An official announcement by the IAAF and UK Athletics was expected Friday.

THG came to light after a track coach provided the U.S. Anti-Doping Agency with a syringe containing the substance. The UCLA lab identified the compound as a steroid deliberately modified to evade detection.

Chambers has been considered a potential gold medal contender in the 2004 Summer Games.

He trained in the United States with Ukrainian-born coach Remi Korchemny. Shear, the athlete's lawyer, said last month that Chambers used Victor Conte, founder of the Bay Area Laboratory Co-Operative, as his "nutritionist."

The USADA has accused Conte of being the source of the THG, a charge he denies. Conte's company is under investigation by a federal grand jury.

Shear said Chambers had never heard of THG and, when he was notified of the positive test early last month, he "immediately challenged" Conte for an explanation.

Chambers was "categorically assured that all supplements he had been given were within the IAAF rules," Shear said.