Eight U.S. athletes who tested positive for substances banned by the International Olympic Committee were not engaged in doping to increase performance and no action will be taken against them.

U.S. Olympic Committee Director of Sports Medicine and Science Dr. Robert Voy said in a letter to The Athletics Congress (TAC), released on Wednesday, that the eight had tested positive in banned substances but in amounts that suggested no intention to violate IOC rules."There will be no action taken - everything was done above board," TAC spokesman Tom Surber told Reuters. None of the athletes involved were named.

The letter, dated Sept. 9 and addressed to TAC executive director Ollan Cassell, said six of the athletes tested positive for pseudoephedrine, ephedrine and phenylpropanolamine, one only for pseudoephedrine, and another only for phenylpropanolamine.

". . . from our experience we feel that when we see positive tests with a combination of substances such as pseudoephedrine, ephedrine and phenylpropanolamine, it suggests that these substances come from some crude drug, probably a herbal preparation or substance," the letter said.

Voy said said in the letter that those substances could be found in hundreds of mineral and vitamin preparations as well as non-prescription cold and sinus remedies that are not banned.

"However, in the case of athletes wishing to use a stimulant to dope, it is possible to use these substances in greater than the recommended doses to get a stimulant effect.

"It is my opinion, in the case of intended doping, we would expect to see levels in excess of 50 to 100 mcg/ml (micrograms per milliliter). These levels would not be excusable," Voy said.