The News of the World said the picture was taken during a November house party while Phelps was visiting the University of South Carolina. During that trip, he went to one of the school's football games and received a big ovation when introduced to the crowd. While the newspaper did not specifically allege that Phelps was smoking pot, it did say the pipe is generally used for that purpose and anonymously quoted a partygoer who said the Olympic champion was "out of control from the moment he got there".

The party occurred nearly three months after the Olympics while Phelps was taking a long break from training, and his actions should have no impact on the eight golds he won at Beijing. He has never tested positive for banned substances and this case is unlikely to fall under any doping rules. Phelps's main sanctions most likely will be financial - perhaps doled out by embarrassed sponsors who might be reconsidering their dealings with the swimmer. Phelps was in Tampa during Super Bowl week to make promotional appearances on behalf of a sponsor. But he left the city before Sunday's game between the Pittsburgh Steelers and Arizona Cardinals, abandoning his original plan to be at Raymond James Stadium. The US Olympic Committee said it was "disappointed in the behaviour recently exhibited by Michael Phelps", who was selected as the group's sportsman of the year. He also was honoured as AP male athlete of the year and his feat in Beijing - breaking Mark Spitz's 36-year-old record for most gold medals in an Olympics - was chosen as the top story of 2008.

"Michael is a role model and he is well aware of the responsibilities and accountability that come with setting a positive example for others, particularly young people," the USOC said in a statement. "In this instance, regrettably, he failed to fulfil those responsibilities." USA Swimming said its Olympic champions were "looked up to by people of all ages, especially young athletes who have their own aspirations and dreams".

"That said," the governing body added, "we realise that none among us is perfect. We hope that Michael can learn from this incident and move forward in a positive way." Phelps was part of a group of elite athletes who agreed to take part in a pilot testing program designed to increase the accuracy of doping tests. His spot in the program could be at risk, said Travis Tygart, head of the US Anti-Doping Agency. "For one of the Olympics' biggest heroes it's disappointing, and we'll evaluate whether he remains in that program," Tygart said. "But some good education comes from this because he's going to suffer some penalties."

Marijuana is viewed differently from performance-enhancing drugs, according to David Howman, executive director of the World Anti-Doping Agency. "It's not banned out of competition. It's only if you test positive in competition," he said. AP