The Operación Puerto blood-doping inquiry has been dropped due to a lack of evidence that a crime was committed under Spanish law, the Spanish press reported Saturday.

Spanish daily El Mundo said Judge Antonio Serrano had dismissed the case, ruling that “there was no law that penalized doping practices under Spanish legislation at the time this case was begun.”

The reports said that while Serrano had determined that blood doping occured, there was no evidence of the practice harming riders' health. That was the requirement under previous Spanish law for charges to be filed against someone who administered doping substances to an athlete.

A new law, which took effect in February, makes it a crime to prescribe, dispense or facilitate use of such substances, regardless of their effect on a person's health.

The official announcement is expected Monday. Another Spanish daily, El Pais, reported that prosecutors intend to appeal Serrano’s ruling.

In May 2006, police raids discovered a number of bags of frozen blood, some containing the banned substance erythropoietin (EPO) along with anabolic steroids and equipment for transfusions.

Documents alleged to detail the doping activities of more than 50 cyclists were also found, leading to the immediate suspension of several high-profile riders, among them Ivan Basso, Jan Ullrich and Francisco Mancebo, all of whom were denied the opportunity to race last year’s Tour de France.

Among the people arrested in the inquiry were doctor Eufemiano Fuentes and Manolo Saiz, former sporting director of the now-disbanded Liberty Seguros team.