Olympic champion Tyler Hamilton of the United States tested positive for blood doping in a second sample from the Tour of Spain, his Phonak team said in Zurich on September 23.

However, the American has been cleared of a doping offence at the Athens Olympic Games after the International Olympic Committee (IOC) considered his B sample on that test had proved inconclusive.

"The laboratory analysis of the B sample was considered as non-conclusive because of a lack of enough intact red blood cells," said an IOC statement on Thursday.

The 33-year-old could still be banned for two years after a positive test for an allegedly illicit blood transfusion following his win on the Tour of Spain's eighth stage time trial earlier in September.

He pulled out of the Tour six days later due to stomach problems.

His team Phonak questioned the testing method, saying it was based on "probability and interpretation measurements" and " uncertainties will remain".

Thus, Hamilton will remain suspended from the team while the probe is carried out, Phonak said.

Source: Xinhua