The highest-ranking official of track and field's world governing body today questioned the accuracy of drug-testing procedures at a time when the sport has been hit with a spate of athletes testing positive for banned substances.

On the eve of the world outdoor track and field championships, International Amateur Athletic Federation President Primo Nebiolo said Wednesday's announcement that Jamaican sprinter Merlene Ottey had tested positive for a well-known anabolic steroid might have been a "mistake."

On Tuesday, Ottey became the fifth athlete in the past month to learn she had tested positive for the anabolic steroid Nandrolone. On Wednesday, when the result became public, Ottey withdrew from the world championships.

The IAAF confirmed that Ottey's "A" urine sample from a meet in Lucerne, Switzerland, on July 5 had turned up positive. Her "B" sample is due to be analyzed shortly at the IOC-accredited laboratory in Lausanne, Switzerland.

Nebiolo said it was unclear whether Ottey, who has won 14 world championship medals, including two golds, "has committed a doping offense or whether there has been some mistake. . . . Personally, I hope this will prove to be just a nightmare for Ottey."

Ottey and several of the other athletes who have tested positive for Nandrolone recently, including British sprinter Linford Christie, have proclaimed their innocence.

The question of whether errors are being made in drug-testing labs is a touchy one among the doctors who perform the tests. Unlike the test for testosterone, a hormone that is produced naturally in the body, the urine test for Nandrolone is extremely reliable, doctors say.

"Do they think we're idiots?" said Christiane Ayotte, the head of the IOC-accredited testing lab in Montreal, quoted recently when questions were raised about Christie's test. ". . . I think I know what is Nandrolone when I find it in a test."

Don Catlin, the head of the IOC-accredited testing lab at UCLA, said he suspects the recent run of Nandrolone positives could be a result of the drug's presence in certain over-the-counter products sold as food supplements in the United States.

Catlin said he considers the products, whose shelf name is 19-norandrostenedione, to be very dangerous steroids even though they can be purchased legally in the United States or over the Internet.

IOC executive board member Jacques Rogge said in a telephone interview last week he didn't consider Nandrolone's presence in over-the-counter products an excuse for athletes who test positive for the substance.

"From a legal point of view," Rogge said, "you still penalize the athlete because, A, he has an unfair advantage and, B, he should know what he takes."

At the recent Pan American Games in Winnipeg, Manitoba, three Cuban weightlifters and a Canadian roller-hockey player tested positive for Nandrolone. Tennis player Petr Korda and soccer player Christophe Dugarry also tested positive for the drug in the past 14 months. Both said they are innocent. Korda, who tested positive last year at Wimbledon, initially was cleared of wrongdoing but now faces a hearing in front of the Court of Arbitration for Sport in Lausanne.

In a different drug-test result, Cuban high jump legend Javier Sotomayer tested positive for cocaine at the Pan Am Games.

"The number of positive tests that have been coming out, it's very bad for our sport," U.S. sprinter Maurice Greene, the world record holder in the 100 meters, said during a news conference here this morning.

"This is a scary thing," American 400-meter runner Jerome Young told the Associated Press. "They need to do more research. I think there was something wrong with the machine. There are too many athletes going down."

In other news, IOC Director General Francois Carrard said the IOC hopes to see the long-awaited independent drug testing agency operating by September. Carrard said the agency would operate as a non-profit foundation and likely would consist of 20 to 35 members of government and international sport. A working group that includes international governmental and sports officials will vote on the specifics of the board at a meeting in early September.

Carrard said the IOC would fund the first year of operation with a $25 million donation. The IOC would have at least one representative on the board but would not be in charge of it, Carrard said. He said he expected the agency to conduct out-of-competition drug testing (perhaps 5,000 tests annually) and to fund drug research.

But the agency, he said, would not replace the existing drug-testing structures. The IOC oversees all testing at the Olympic Games. World governing bodies oversee testing at their world championships.