American sprinter Bernard Williams tested positive for a metabolite of cannabis at a meeting in Seville in June, the U.S. Anti-Doping Agency (USADA) said on Monday.

Williams, a gold medal winner in the U.S. 4x100 relay team at the Sydney Olympics [ Images ], has received a warning but remains eligible to compete in Athens.

A USADA statement said Williams had tested positive for a metabolite of cannabis or tetrahydrocannabinol (THC), a prohibited substance under the International Association of Athletics Federations (IAAF) rules.

It added: "Following consultation with the IAAF, Williams, 26, received a public warning, in accordance with the IAAF rules for a first offence.

"In addition, he is disqualified from his second-place finish in the 200 metres at the (Seville) meeting. Williams is eligible to compete at the 2004 Olympic Games [ Images ] in Athens."

The statement said that in accordance with the USADA Protocol for Olympic Movement Testing, the case was referred to USADA on August 3 for adjudication from the USA Track and Field (USATF), which received the case from the IAAF.

USADA became the independent anti-doping agency for U.S. athletes for the Olympic movement in October 2000.