Barcelona legend Johan Cruyff called on Monday for Real Madrid to apologise after they were implicated in doping accusations against his former Catalan club.
A Spanish radio station, COPE, quoted an unidentified Real Madrid "representative" as saying the club had asked the football federation to take drug testing more seriously.
According to the radio station's March 13 report, Real Madrid could not understand how doctors with "questionable reputations" could work for Barcelona.
It also cast doubt on doctors working for Valencia.
Barcelona and Valencia have angrily denied the allegations and threatened legal action against the radio station, which has apologised for questioning the clubs' honesty without actually retracting the report.
"The accusation is too serious, too brutal, for there not to have been apologies, and well-presented too," Cruyff said in his weekly column for the Catalan daily El Periodico de Catalunya.
Apologies should have been given "by Real Madrid themselves," Cruyff said, not for being the accusing party but because they were implicated in the row albeit by others.
Real president Florentino Perez reportedly personally telephoned his counterpart at Barcelona, Sandro Rosell, to deny he was the source of the radio station's story.
Rivalry and sportsmanship were not mutually exclusive, Cruyff said, praising rival clubs including Real Madrid for showing support for Barcelona defender Eric Abidal, who had surgery to remove a liver tumour on Thursday.
Cruyff said his views about sportsmanship were confirmed by the doping accusations and, to a lesser extent, by the way the press poured scorn on Barcelona and Real Madrid's rivals in the Champions League quarterfinals.
"It is hard for a sports player to show a gratuitous lack of due public respect to any rival. For those who are off the field, that is to say, those who are not and have not been sports players, it comes too easily."
A three-time European Footballer of the Year, 63-year-old Cruyff started his career as a teenager at Ajax before going on to enjoy huge success with Barcelona, whom he then coached to the 1992 European Cup and four straight league titles between 1991 and 1994.