A Madrid court has ordered the Operation Puerto investigation into a doping ring in cycling to be reopened because of evidence of possible offences against public health by doctors implicated in the probe.

However, the court agreed on Thursday with the original ruling that neither the cyclists nor those who gave them doping substances were guilty of offences under the Spanish law in force when the inquiry began.

The court asked investigating judge Antonio Serrano to order a report into the risks of conserving blood in conditions not regulated by the health service.

It added that although the riders had done nothing illegal, sanctions could still be taken by sporting authorities.

In his original ruling last March, judge Serrano closed the case saying that despite there being proof of doping practices, there was insufficient evidence to prosecute.

Doping was not punishable under Spanish law when the charges were brought in May 2006. Serrano said the case was not subject to new tougher legislation introduced to deal with people who supply and administer drugs in sport.

Operation Puerto was launched after raids in Madrid and Zaragoza, where police found large quantities of anabolic steroids, laboratory equipment used for blood transfusions and more than 200 bags of code-named blood, some of which were linked to leading cyclists.

Spain's Civil Guard listed more than 50 riders implicated in the affair, including former Tour de France winner Jan Ullrich, Tour of Spain winner Roberto Heras and Giro d'Italia victor Ivan Basso.

The former sporting director of the now defunct Liberty Seguros team, Manolo Saiz, doctor Eufemiano Fuentes and his colleague Jose Luis Merino Batres were among those questioned by police.

Reuters