VIENNA, Jan 31, 2008 (AFP) - Austrian State Secretary for Sports Reinhold Lopatka said Thursday he could clear a Vienna laboratory suspected by the World Anti-Doping Agency (WADA) of running a blood bank for doping purposes.

'There isn't any hint of proof that doping was conducted at this institute. There isn't any witness... there's nothing, and if there's nothing, the investigators won't discover anything,' he told national radio.

Lopatka said he had shared his thoughts with WADA, which first suspected the Vienna-based Human Plasma of running a doping blood bank and alerted Austrian authorities in November.

Lopatka said he had become convinced of the laboratory's innocence after speaking to 'investigators, athletes and employees at the company.'

But the Vienna prosecutor's office remained cautious, saying the inquiry was under way.

'Mr. Lopatka must have elements we don't have. As far as we are concerned, we are waiting for the results of the investigation,' a spokesman for the prosecutor's office, Gerhard Jarosch, told AFP.

Human Plasma is being investigated in Italy and Austria following allegations by WADA that it supplied so-called 'dry blood' to athletes for doping purposes.

'There are good reasons to believe that... this company supplies athletes who are re-injecting blood for doping purposes,' WADA's former president Dick Pound wrote in a letter to Lopatka published in the Austrian daily Kurier.

The laboratory is also under scrutiny in Italy for possible involvement in doping at the Turin Winter Olympics in 2006.

Human Plasma, which has denied all the allegations against it, sued one of its main accusers, the president of the Austrian Ski Federation's disciplinary committee Arnold Riebenbauer, in mid-January, for spreading 'untruths.'

Four cyclists who had been accused by German public television ARD of using the laboratory's services -- the Dane Michael Rasmussen, Michael Boogerd of the Netherlands, Russia's Denis Menchov and Austria's Georg Totschnig -- have officially denied the accusations.

Doping is not a crime in Austria and experts have accused the country's authorities of being too soft in such cases.