UK Anti-Doping's chief has criticised a Spanish court's order that evidence in the case of Eufemiano Fuentes be destroyed.
Fuentes, a doctor specialising in sports medicine, received a suspended one-year jail term for providing blood-doping services to cyclists.
Some 211 blood bags from 35 different people were seized as part of Operacion Puerto when Spanish police raided Fuente's laboratory in 2006. However, the Madrid judge has rejected requests from anti-doping authorities and international sports federations to be allowed to analyse the blood bags and has ordered that they be destroyed.
That decision has been blasted by UKAD chief executive Andy Parkinson.
He said: "We are disappointed in the decision by the Spanish authorities today.
"Dr Fuentes has admitted to having been involved in multiple prohibited doping activities, and linked with multiple unnamed athletes. It therefore cannot be right that these names will remain unknown and that no immediate action can be taken by the anti-doping community to protect our clean athletes."
Anti-doping organisations who had hoped to identify other drugs cheats, and sources in the World Anti-Doping Agency (WADA) are hopeful that the Spanish anti-doping body will be able to appeal against the decision of the Madrid court.
Fuentes has also been banned from working as a doctor in sports medicine for four years at the end of the Operacion Puerto trial in Madrid.
The court also sentenced former cycling team official Ignacio Labarta to four months in jail, and acquitted three others on trial. Fuentes had been accused of running one of the biggest doping rings in sport.
Although the investigation focused on cycling, WADA and the Spanish anti-doping agency had asked for access to the evidence to see if athletes from other sports were involved.
During his trial, Fuentes said that as well as cyclists, he had worked with runners, footballers and boxers, though he did not admit to facilitating doping.