Profesionnal cyclists have called for tougher sanctions for dope cheats, the sport's governing body has said, as it seeks to restore its reputation after the damaging Lance Armstrong drug scandal.

Madrid - A Spanish doctor accused of masterminding one of sport's biggest blood doping rackets on Wednesday said he had no idea of the origin of banned performance enhancer EPO found in some blood packs seized from two of his Madrid apartments.

The traces of EPO found in the packs of some athletes' blood were tiny and could have resulted from ingestions before the blood was extracted, the 57-year-old doctor, Eufemiano Fuentes, told a Madrid court.

The use of EPO, or erythropoietin, is banned from sports because it can improve the delivery of oxygen to the muscles of athletes, especially in endurance disciplines such as cycling.

Police detained Fuentes in 2006 when they seized 200 bags of blood and plasma, and other evidence of performance-enhancing transfusions, in an investigation dubbed “Operation Puerto”.

“Of the 92 packs of plasma analysed, eight had levels of EPO that were above normal. But it was minimal, the elevation of those levels was in the thousandths of a unit when EPO is used in medicine in units,” Fuentes said.

The doctor denied knowing from where the EPO originated.

“The excess of EPO could have come from ingestion of the substance before extraction,” he told the court.

Fuentes, his sister Yolanda and three other defendants from cycling teams are charged with endangering public health rather than incitement to doping, which was not a crime in Spain at the time of the arrests.

The doctor denies that his treatment endangered the cyclists' health.

On Tuesday, the doctor from the Canary Islands said ampules of EPO found in his home were for use within his family.

“It was for my daughter, who had cancer and was undergoing chemotherapy,” he said.

Fuentes said he re-injected an athlete's own blood only if it was needed in order to regain a normal red blood cell count, and not to improve sporting performance.