Four-time Vuelta a España winner Roberto Heras and his attorney cried foul on Wednesday after a Spanish laboratory said there had been a delay in the analysis of his B sample from the 2005 Vuelta's 20th-stage time trial.

Heras, whose A sample tested positive for EPO after that penultimate stage, has maintained his innocence, arguing that there had been a mix-up in the laboratory and that he was confident of being cleared.

During a press conference Wednesday, Heras told the Reuters news agency that the lab was "unable to reach a conclusion."

"I expected a negative test, but what has happened is that they could not confirm anything," the 31-year-old Spaniard said. "I want to reiterate once again that I've never taken a doping substance in my life. I've got a completely clear conscience and I insist I've never taken EPO or anything else in my career."

Laboratory spokesman Francisco Rodriguez said the testing process "is not quite finished," adding, "There's been a delay only because we had to take more measures."

Heras's lawyer, Jose Maria Buxeda, told Reuters the delay "provides clear evidence that the method is flawed. It doesn't offer any guarantees."

"The image of the test could not be read," he continued. "So the result should be that EPO has not been detected. The director of the laboratory has decided to repeat the analysis again and in principle the result will be announced on Friday, but what guarantees will that give us?"

Heras told Reuters "it would have been madness" to dope in the penultimate stage with a lead of more than four minutes.

"I think it is right that there are controls but this method is clearly unreliable," he said. "I want people to know that Roberto Heras is a sportsman who has always competed cleanly. Proving my innocence is far more important for me than winning a fourth Vuelta and I will do what it takes to do that."

If the second test comes back negative, Heras will retain his record fourth Vuelta title. If positive, he would be slapped with a two-year racing ban and stripped of the title. Runner-up Denis Menchov (Rabobank) would be named winner.