A Spanish judge is seeking a gag order on 12 media outlets that leaked documents alleging stars like Cristiano Ronaldo could be involved in tax evasion.

Madrid: A Spanish judge is seeking a gag order on 12 European media outlets that leaked documents alleging football stars like Cristiano Ronaldo could have been involved in a multimillion-euro tax evasion system.

The injunction, seen by AFP on Monday, claims that the so-called "Football Leaks" published last week could constitute an offence against the right to privacy as they were allegedly obtained through a cyber-attack on Senn Ferrero, a firm advising sports personalities on tax.

In it, Judge Arturo Zamarriego seeks European judicial cooperation to stop all 12 outlets that form part of the European Investigative Collaborations (EIC) consortium -- including Spain's El Mundo, Germany's Der Spiegel and France's Mediapart -- from publishing the information.

The first batch of leaks unveiled Friday, the same day the injunction was issued, centred on "a system" allegedly put in place by Jorge Mendes, the agent of Ronaldo and Jose Mourinho, current Manchester United coach.

They allege for instance that Real Madrid and Portuguese star Ronaldo could have "hidden 150 million euros (from image rights) in tax havens in Switzerland and the British Virgin Islands."

"On this amount, the striker paid only 5.6 million euros in taxes, or barely four percent," the report says.

Both Ronaldo and Mourinho maintain they have fully complied with Spanish and British fiscal requirements.

Still, Spanish tax authorities are investigating the allegations where Ronaldo is concerned.

On Friday, Mendes's company Gestifute said that the documents leaked came from March "cyber-attacks" on "a number of societies linked to the world of football."

As such, the injunction seeks to "paralyse and/or ban the publication, whether in printed or digital versions, of confidential information of a personal, financial, fiscal and/or legal nature of clients of Senn Ferrero, which the European Investigative Collaborations consortium of journalists could have had access to."

In a story Monday, though, Mediapart refuted the cyber-attack allegations, saying the source at the origin of "Football Leaks" denied this.

"This is an attempt at censorship on the scale of an entire continent," it wrote.

In weeks to come, the media organisations, which also include The Sunday Times in Britain, say they will also publish allegations of prostitution and exploitation of minors in football.

More than 18 million leaked documents have been examined in the expose.