MADRID (REUTERS) - The head of Spain's professional soccer league (LFP), Jose Luis Astiazaran, has denied allegations made in As sports daily on Monday that he was complicit in the provision of banned substances to players while president of Real Sociedad.

As sports daily published an interview with Inaki Badiola, who had a stint as Sociedad president in 2008, in which he said two club doctors had been given money off the books to buy banned drugs in the six years before he took over and possibly earlier.

The LFP published a lengthy statement from Astiazaran responding to the allegations in which he said he had neither knowledge nor suspicion of illegal practices by medical staff during his time as Sociedad president between 2001 and 2005.

"Real Sociedad have always, and obviously under my presidency, collaborated closely with authorities charged with testing for doping and there has never been any incident in the numerous anti-doping tests taken," Astiazaran said.

"Given the statements and falsities expressed by Mr. Badiola, I reserve the right to begin whatever legal proceedings will be necessary to defend my honour," he added.

The Operation Puerto trial in Madrid, into doping in cycling, is being closely watched in Spain and beyond as anti-doping authorities are hopeful it may uncover evidence of illegal drug-taking in other sports.

One of the many code names in documents seized in the Puerto investigation was "RSOC" and Badiola told As sports daily the initials likely referred to San Sebastian-based Sociedad.

In an emailed response from their press office on Sunday, Sociedad said they knew nothing about a possible link between the initials and the club.