Spanish footballing giants Barcelona and Valencia on Monday rejected allegations by a Spanish radio station that they may be involved in doping.

Barcelona "wishes to publicly express its total indignation at these unfounded references which link the club to doping practices" while Valencia described the allegations on the Catholic radio station Cadena Cope as "false".

Cadena Cope on Sunday quoted a "representative" of Real Madrid, who was not identified, as saying the club planned to "ask the Spanish football federation for serious anti-doping controls".

It said Real could not understand how Eufemiano Fuentes, a doctor who was one of six people charged in December with trafficking offences in an athletics doping probe dubbed Operation Galgo, could have worked for "a first division club, specifically Valencia, curiously when it won two championships".

Valencia won the Spanish league in 2002 and 2004.

Cadena Cope also said Real "could not understand how other doctors of a doubtful reputation can work for FC Barcelona".

Spain's Secretary of State for Sport, Jaime Lissavetzky, said he was not aware of any request from Real Madrid to change doping rules.

"Spanish football is clean. We follow every guideline set out by FIFA and UEFA in this regard," he said.

Barcelona said in a statement it "is demanding an immediate rectification and wishes to let it be known that its legal department is studying possible legal action to defend the club's honor, alongside that of its coaching staff, players and medical staff and is prepared to take such action to its final consequences".

Valencia said it had "never worked" with Fuentes or been "advised directly or indirectly by him".

A Real spokeswoman said "there is no official announcement at the moment" from the club in response to the radio report.