Michele Verdier, the International Olympic Committee spokeswoman, said it would be up to the US Track and Field Federation to determine what other sanctions might be taken against Dasse. Meanwhile, the US Olympic Committee said that Dasse, who finished eighth in her preliminary heat and failed to qualify for the final, had already left Barcelona.
'We are saddened any time there is a positive drug test for any American athlete,' Dr Harvey Schiller, the USOC's secretary- general, said. Prince Alexandre de Merode, chairman of the IOC's medical commission, said the test had been carried out on Wednesday and that Dasse pointed out that she had stopped taking the product three days earlier. 'She said it was given to her by a friend she trusts. She didn't try to lie.'
Clenbuterol is banned because it is an anabolic-type agent that promotes the healing and growing of muscle. One known use is in the beefing-up of cattle in the United States, while in Germany it is available as a licensed asthma drug.
It was the US hammer thrower Jud Logan, whose fourth-place finish surprised observers, who was thrown out earlier and had the dubious distinction of becoming the first athlete from his country to test positive for a banned substance at the Olympics in 16 years.
Two other competitors have also tested positive in Barcelona - Wu Dan, a member of the Chinese women's volleyball team whose test showed traces of strychnine, and the Unified Team's Madina Biktagirova, fourth in the marathon but tested positive for Norephedrine. Wu has escaped with a three-months suspension, the International Volleyball Federation saying it had imposed a lenient ban because she had inadvertently taken a Chinese folk tonic.
In relation to these Games, the Clenbuterol list includes two British weightlifters, who were sent home following results of a test in Britain before the Olympics, and the sprinter Katrin Krabbe, tested positive in Germany last month.
Britain also suffered another loss when Jason Livingston was expelled from Barcelona after Methandianone was found in an out-of-competition test on 15 July.