Track and field's world governing body threw its support behind Maurice Greene and dismissed doping allegations against the former Olympic and world sprint champion.

Greene also denied the accusations, which were made by a witness in a US government investigation and reported on Saturday in The New York Times.

"None of this is new," International Association of Athletics Federations spokesman Nick Davies said. "There is no reason to take action against Maurice."

Davies said the IAAF would continue to use Greene as one of its goodwill ambassadors to promote the sport in the run-up to the Beijing Olympics.

"With every ambassador we do an immediate check with the doping department," Davies said from IAAF headquarters in Monaco. "In this case, they said, no we don't have anything."

A witness in a US government investigation into sports doping said he advised and supplied banned substances to athletics coach Trevor Graham and his athletes, including Greene and Marion Jones, The New York Times reported.

"I read about this guy and this rumor four years ago," Davies said.

Citing court filings, The New York Times said that Angel Guillermo Heredia, identified as Source A in the felony indictment, agreed to be a cooperating witness when investigators confronted him with evidence of his own drug trafficking and money laundering.

It said Heredia said he has provided prosecutors with the names of many elite athletes and Olympic medal winners, as well as documentation.

Heredia identified 12 Olympic medalists, including Greene, the two-time Olympic gold medalist and five-time world champion who has never been previously linked to doping. Greene, who retired in February, never failed a doping test.

Greene said that he had met with Heredia but did not receive or use any drugs.

"This is a bad situation for me. My name's coming up in something and it's not true. ... I have met him before and when he was talking to me, I told him I don't believe in this stuff," he told London's Daily Telegraph.

(Agencies April 16, 2008)