Spanish track cyclist Maria Isabel Moreno has become the first competitor in Beijing to fail a drugs test.
Moreno, 27, who would have been a rival of Britain’s gold medallist Nicole Cooke, tested positive for the blood-doping agent EPO.
The drugs test was carried out on July 31 and she left Beijing later that day without offering an explanation.
IOC communications director Giselle Davies said: “She was tested in the Village and she had already left China that evening before having had the result.
“The test has come back positive for EPO. The disciplinary commission has ruled that she should be excluded from the Games and have her accreditation withdrawn.”
The IOC have now passed the case to the UCI cycling federation to follow up in terms of imposing a ban.
Reports in Spain last week said the cyclist, also known as Maribel Moreno, had dropped out after suffering an “anxiety attack”.