The EU ombudsman Tuesday asked the European Commission to speed up a state aid probe into seven Spanish football clubs, including Barcelona and Real Madrid, amid claims of conflicts of interest.
Ombudsman Emily O'Reilly, who investigates complaints against EU institutions, said the Commission had "failed to act on this complaint for more than four years".
"Not only is this bad administration, but to the European public it can look like a conflict of interest given the Commissioner's strong links to one of the football clubs in question," she said.
Investors in other European football clubs alleged that the Commission's inaction might be linked to the fact that the commissioner responsible supports one of the teams in question and was a minister in the Spanish government that decided on the tax advantages at the time.
Now Competition Commissioner -- and Athletic Bilbao fan -- Joaquin Almunia is in charge of opening infringement proceedings against Spain concerning alleged unfair tax advantages, said to amount to several billion euros.
Almunia's spokesman Antoine Colombani on Tuesday rejected O'Reilly's criticism.
The commissioner "holds that any allegation of conflict of interest in this matter is unacceptable", Colombani told a news briefing.
Spain's Foreign Minister Jose Manuel Garcia-Margallo had announced on Monday that the European Commission would on Wednesday launch a formal investigation into the seven clubs.
It would be the first step to a procedure for violation of EU rules and could lead to sanctions if these rules were in fact broken.
Madrid appeared concerned about the consequences of the Brussels decision and Garcia-Margallo said the government would "defend the clubs to the end".
"As far as I know there was nothing illegal," said the minister. "But I am concerned about the prejudice that the clubs may suffer."
The focus of the investigation is on whether the tax rate imposed on four clubs -- Real Madrid, Barcelona, Athletic Bilbao and Osasuna -- complies with European law.
Brussels is also looking into loans granted by the Valencian Community to Valencia, Hercules and Elche.
And Almunia wants the investigation to clarify whether or not Real Madrid and Athletic Bilbao real estate operations were proper.
For her part, the ombudsman said she had not looked into the "merits of the allegations concerning the breach of State Aid rules."
"I trust, however, that the Commission will decide to open an investigation tomorrow [Wednesday] in order to investigate the facts and dispel any suspicions," said O'Reilly.