By Alan Baldwin

LONDON (Reuters) - Britain's top Olympic hope in Greco-Roman wrestling, Ukraine-born Myroslav Dykun, has been suspended and risks missing London 2012 after failing a dope test, British Wrestling said on Thursday.

"He's tested positive with his 'A' sample and has been suspended with immediate effect. We believe it's from the amphetamines group," British Wrestling chief executive Colin Nicholson told Reuters.

The 2010 Commonwealth Games 66kg gold medalist faces a likely two-year ban if a 'B' test confirms the initial positive result.

The British Olympic Association, which this week lost a battle to impose lifetime Olympic bans on drugs cheats little more than two months away from the start of the London Games on July 27, had no immediate comment.

Nicholson said British Wrestling was committed to clean competition and was fully supportive of the UK drug testing program.

"We will not tolerate such behavior from anyone, that goes whether its performance-enhancing or recreational," he declared.

Dubbed a "Plastic Brit" by some in the media, who have accused British Wrestling of importing talent to raise their standing and win medals, the 29-year-old is one of several Ukrainian-born grapplers set for the Games after marrying Britons.

One source close to the sport said the failed test, if backed up by the B sample, would be a "kick in the teeth" and commentators agreed.

"Dykun's positive test will surely provoke an investigation into how much we want to triumph at these Games and what we are prepared to sacrifice to win," Daily Mail columnist Martin Samuel said.

"Too much, it would seem, if we would rather fast-track cheats than send out our best to be beaten."

Nicholson said the nationality debate was misleading, however.

He pointed out that marriage between athletes in a sport, like any workplace, was not unusual and the ones referred to in the media were spread out over a 10-year period and had "nothing to do with the world class program."

"British Wrestling had never orchestrated any marriage," he added.

"Myroslav Dykun has been here since 2003, before there was any London bid, and has been wrestling for Britain since then," Nicholson said. "So he cannot be accused of coming to Britain for the Games.

"He has a full UK passport and as a UK passport holder he's eligible for selection. If he's the best, we have to select him."

British Wrestling has yet to name its athletes for Team GB at the London Games.

(Reporting by Alan Baldwin; Editing by Ossian Shine/John O'Brien)