Birmingham's Olympic gold-medallist Mark Lewis-Francis has escaped a ban after testing positive for cannabis at this year's Spar European Indoor Championships.

After finishing second behind Athens 4x100metres relay team-mate Jason Gardener on March 5, the Darlaston athlete underwent a compulsory drugs test where small traces of the drug were detected in his sample.

He has been stripped of his silver medal and given a public warning by UK Athletics as a result but he remains free to compete after it was accepted the drug could not have been taken to enhance his performance.

Meanwhile, the athlete has denied taking the drug, telling the Press Association this morning: "I do not smoke cannabis. 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."

The 22-year-old former world junior champion accepted the punishment and waived his right to a disciplinary hearing which he was entitled to under UK Athletics and International Association of Athletic Federations anti-doping rules.

However, the consequences were potentially serious for Lewis-Francis.

"An athlete testing positive for cannabis should be subject to a sanction which can range from just a public warning and disqualification from the event, to a maximum of two years," said Nick Davies, the IAAF's media director.

"The IAAF considers every case individually and it is up to the athlete to demonstrate that the substance was not taken to enhance performance."

This clearly was felt about Lewis-Francis, who is based in the Midlands and is the second member of the Birchfield Harriers club to have been given a public warning by UK Athletics after testing positive for cannabis.

Jonathan Moore, the 2001 world youth triple-jump champion, also failed a test after competing at a meeting in Merksem, Belgium last September, but also claimed he had ingested the drug passively.

Two of America's top sprinters, Olympic 200m runner-up Bernard Williams and the world 200m champion John Capel, also received public warnings for the offence last year.

In no way does Lewis-Francis's infringement of the anti-doping regulations put him into the same category as 1996 Olympic champion Linford Christie and European title-holder Dwain Chambers.

Christie was banned for two years after failing a drugs test for nandrolone after an indoor meeting in Dortmund six years ago.

Chambers' failed test was the first involving some of the world's greatest athletes who were found to have used the designer steroid tetrahydrogestrinone (THG).

He was banned for two years, a suspension which expires in November this year, and the 4x100m relay team - including Lewis-Francis - were stripped of their silver medals at the World Championships two years ago.

UK Athletics were only prepared to comment via a statement on their website.

It said: "Mark Lewis-Francis provided a sample at the European Indoor Championships in Madrid, Spain on March 5, 2005. The analysis of the sample identified the presence of cannabis. Cannabis is included as a specified substance on the 2004 WADA Prohibited List.

"UK Athletics' and the IAAF's anti-doping rules allow a punishment of a public warning (without a period of ineligibility) to be imposed where the substance is classified as a specified substance on the prohibited list, it is the athlete's first anti-doping rule violation and where UK Athletics is satisfied that there was no intention to enhance performance."

The statement added: "UK Athletics and the IAAF are satisfied that these factors all applied in Mark Lewis-Francis case.

"UK Athletics hereby issues Mark Lewis-Francis with a public warning for a finding of cannabis in a sample.

"UK Athletics confirms that the athlete is disqualified from that competition. No period of ineligibility has been imposed and the athlete is free to compete."