Record-breaking Olympic swimmer Michael Phelps issued an apology on Sunday after a British newspaper published a photograph purportedly1 showing him smoking marijuana.

But that might not be enough for some sports officials and fans who claim he has tainted2 his image as a role model.

I engaged in behavior which was regrettable and demonstrated bad judgment, Phelps, the winner of eight gold medals at the Beijing Olympics, said in a statement in response to the News of the World photograph.

Phelps, who has never failed a doping test, promised there would not be a repeat.

I'm 23 years old and despite the successes I've had in the pool, I acted in a youthful and inappropriate way, not in the manner people have come to expect from me, he said.

For this, I am sorry. I promise my fans and the public it will not happen again.

US officials said the news was disappointing but stressed that smoking marijuana outside of a competition did not break any doping rules.

Travis Tygart, chief executive of the US anti-doping agency, said: Obviously it's very disappointing and a terrible decision by Michael. To a certain extent, he let down the world.

Phelps won eight events in Beijing to take his career gold medal tally3 to 14, making him the most successful athlete in the history of the Modern Olympics.

Many Chinese sports fans were surprised at the news.

In a poll of 13,000 people conducted by Sina.com, nearly two-thirds said Phelps had behaved inappropriately.

Phelps set a very bad example for young people, police officer Kang Jianghua, 30, said yesterday.

But not everyone thought the incident was serious.

More than 30 percent of the voters said they thought it is common for athletes to take drugs.

I don't think it's a big deal, public servant Yan Jun said. I think he's under a lot of pressure. We should be more tolerant.