A group of European media outlets on Friday published what it claims are details of tax arrangements made by several top soccer players and coaches, including Real Madrid forward Cristiano Ronaldo, Manchester United manager Jose Mourinho and Arsenal midfielder Mesut Ozil.

The news outlets, which include German weekly Der Spiegel and Spanish daily El Mundo, cited documents provided by the website Football Leaks, which has in the past claimed that some players and coaches made transactions that could suggest financial impropriety.

The group, which goes by the name European Investigative Collaborations, said it plans to release further reports in the coming days and weeks.

The company of Ronaldo's and Mourinho's agent, Jorge Mendes, released a statement denying any wrongdoing by his clients.

"Both Cristiano Ronaldo and Jose Mourinho are in compliance with their fiscal obligations in Spain and in the United Kingdom," said the statement by Mendes' company Gestifute, which was released Thursday after a report in Spain accused Ronaldo of wrongdoing. "Cristiano Ronaldo and Jose Mourinho have never been involved in any legal process related to any fiscal crime."

It added that it would take legal action against "any insinuation or accusation of that nature related" to Ronaldo or Mourinho.

El Mundo reported that Spain's tax authority has been investigating some of Mendes' clients for some time.

Many top players in Spain have had to deal with local tax authorities recently, including Barcelona's stars Neymar and Lionel Messi.

Jose Mourinho's agent has denied any wrongdoing (Getty)

In July, Messi and his father were sentenced to 21 months in prison for tax fraud, although they were not sent to jail because sentences of less than two years for first offences are usually suspended in Spain.

Neymar and his father recently found out that they are each facing a two-year prison sentence and a $10.6 million fine on corruption charges related to alleged irregularities during his transfer from Brazilian club Santos to Barcelona in 2013. They have denied wrongdoing.

In June, Barcelona paid a fine of $5.8 million in a separate case after acknowledging to the local tax authority it made "an error in the fiscal planning of the player's transfer."

Last month, Spanish prosecutors said they are seeking a prison term of more than 10 years for former Barcelona striker Samuel Eto'o for alleged tax crimes committed when he played for the Catalan club.

Also this year, Barcelona midfielder Javier Mascherano was handed a suspended one-year sentence for tax fraud, and former defender Adriano was also charged with tax irregularities.

