LONDON -- Two drugs under scrutiny in sports -- modafinil and THG -- are part of a pattern of doping abuse in the United States, a top track and field executive said Monday.

Arne Ljungqvist, the IAAF's medical commission chief, said the evidence suggests a link between the substances.

Modafinil is the drug sprinter Kelli White says she took for a sleep disorder. Tetrahydrogestrinone, or THG, is a previously undetectable designer steroid that has turned up in the samples of several track and field athletes.

"What emerges now is a pattern," Ljungqvist told The Associated Press by phone from Sweden. "People have taken THG for obvious reasons -- it's been designed with the intent not to be discovered.

"And modafinil seems to have become a fashionable stimulant among certain athletes as well. It's a pattern I've seen before, where drugs have become popular and we find them."

The Washington Post, citing unidentified international sources with knowledge of the results, reported on its Web site Monday night that American sprinter Chryste Gaines tested positive for modafinil at the U.S. track and field championships in July.

Calvin Harrison, an Olympic and world relay gold medalist, also tested positive for the stimulant this past summer, a source close to a U.S. doping investigation, told the AP on Saturday on condition of anonymity.

Harrison, still awaiting the result of his backup B sample, was tested at the U.S. national championships in June at Stanford, Calif.

Modafinil first came to prominence in August when White tested positive for the drug at the world championships in Paris. She stands to be stripped of her 100-meter and 200 titles.

White said she took modafinil on prescription from her personal doctor to combat narcolepsy. The International Association of Athletics Federations charged her with a doping offense and submitted her case to U.S. authorities for disciplinary action.

Another U.S. athlete, Chris Phillips, who finished fifth in the 110 hurdles at the worlds, also tested positive for modafinil at the Paris meet. Harrison ran the opening leg of the 1,600 relay at the worlds.

Ljungqvist said the IAAF's penalty for modafinil is a public warning and disqualification from the competition where the test took place -- but no ban.

Samples from the U.S. championships were retested after the UCLA doping control laboratory, acting on a tip, devised a test for THG. While retesting, U.S. officials discovered several positives for modafinil.

Ljungqvist said the IAAF had been "directly or indirectly" informed of six to eight modafinil cases.

Referring to White's narcolepsy defense, he said: "It comes into a different sort of light when it becomes known that modafinil has been taken by a number of athletes."

On another drug issue, Ljungqvist said USA Track & Field still has not provided the required documents on Jerome Young's 1999 positive steroid test -- a case that could cost the United States an Olympic relay gold medal. Ljungqvist set a deadline of Nov. 21 for USATF to comply.

Young tested positive for the steroid nandrolone but was cleared on appeal by USATF officials. He went on to win a 1,600 relay gold medal at the 2000 Olympics.

USATF officials have declined to provide the information, citing confidentiality rules at the time.