Two of Greece's top contenders for Olympic track medals have been injured in a motorcycle accident. The incident happened just hours after the athletes could not be located for drug tests in the athletes' village on Thursday.

Reigning 200 meter champion Kostas Kenteris and Greek sprinter Katerina Thanou, who won the silver medal in the women's 100 meters at the 2000 Summer Games in Sydney, were both hospitalized with minor injuries. It is not clear if their injuries will prevent them from competing, even if they are cleared of and doping problems. Before the accident, International Olympic Committee President Jacques Rogge had set up a three-member disciplinary committee to investigate an alleged anti-doping rule violation involving the two Greeks.

Neither athlete has ever tested positive for drugs. But refusal to take a drug test is considered the same as a positive test, which can result in a suspension. Two missed tests can also result in a ban under IOC doping regulations.

Kenteris is a national hero since his surprise victory in Sydney four years ago. He had been widely expected to have the honor of lighting the Olympic flame at Friday's opening ceremony.

His absence would dash Greek hopes for a grand Games after a late push of construction and preparation had silenced critics of Athens'sometimes chaotic build-up.

Earlier Thursday, World Anti-Doping Agency chief Dick Pound announced testing will be conducted to look for human growth hormone at the Athens games.

"There is a very serious problem. And it is a sleazy thing," he said. "Because it is not a case of the occasional athlete taking a cold medicine or supplement by accident."

Some athletes have used HGH to produce muscle. It has previously been undetectable, and it is uncertain if the new test will be completely reliable. But Pound is hoping users will not get away.

"I would rather have them be faced with a very unpleasant surprise if they try and use it here," he said.

Pound also criticized USA Track and Field, saying the federation is not credible because of a recent string of positive dope tests.

He did praise the U.S. Anti-Doping Agency for causing what he called a real sea of change. He said USADA has caught more than one-dozen athletes cheating since last year and he hopes to see a better approach in the United States.