THE anchorman in Britain's gold-medal Olympic relay team, Mark Lewis-Francis, was convicted of a doping offence yesterday, writes .

Though the former world junior champion pleaded that cannabis was in his system as a result of passive smoking, he was stripped of the silver medal he won in the 60 metres at the European Indoor Championships in Madrid where he ran second to Athens relay colleague Jason Gardener.

He received a public warning, but escaped suspension as it was a first offence and cannabis is not considered to be performance-enhancing. He could have been suspended for a year, but remains free to compete. A further cannabis offence would bring a two-year ban.

It is the second time in 19 months that a UK sprinter has forfeited a championship medal because of a doping offence.

European 100m champion Dwain Chambers was suspended for two years when a designer steroid was found in his system. He lost his gold, and Britain forfeited relay silver.

"I do not smoke cannabis, " said the 22-year-old Lewis-Francis who waived his right to a disciplinary hearing. "My only explanation is that I may, without realising it, have been in the presence of people who were smoking cannabis and that I passively inhaled their smoke. I have not knowingly taken this substance, and have not attained any performance-enhancing benefits."

Last year his Birchfield clubmate, Jonathan Moore, also escaped a ban, after a positive test for cannabis in Belgium.

Moore, who won World and Commonwealth youth triple jump titles, also blamed passive smoking and received a public warning.

The same defence was offered by Ross Rebagliati, Canadian winner of the 1998 Olympic snowboard title. He kept his gold medal after the Court of Arbitration for Sport ruled there was a loophole in the rules. There was no agreement between the IOC and ski federation on tests for marijuana.

Last year, the Olympic 200m runner-up Bernard Williams and World 200m champion John Capel (both USA) also received public warnings but no ban for the same offence.