In a statement released on Tuesday, Madrid's regional state prosecutor accused Ronaldo, 32, of four counts of tax fraud from 2011 to 2014.

It said the Portugal captain "took advantage of a business structure created in 2010 to hide from fiscal authorities income generated in Spain from image rights."

The statement said Ronaldo used what it deems a shell company in the Virgin Islands to "create a screen in order to hide his total income from Spain's Tax Office."

Ronaldo's agency had previously said he was up to date on his taxes. Last month, tax officials said he adjusted his tax declarations and paid an extra €6m in 2014.

Ronaldo's agency Gestifute had previously said he was up to date on his taxes, and it defended him again on Tuesday by saying that he had maintained the same financial planning in Spain that he had while playing for Manchester United before joining Madrid in 2009.

"There is no offshore structure for evading taxes," Gestifute said in a statement. "There has never been concealment, or the slightest intention to conceal."

Speaking to El Chiringuito TV before the Champions League final, Ronaldo said he was not losing any sleep over the possibility of being charged.

"I am very relaxed about it -- the truth is I'm very, very relaxed," Ronaldo said. "I know that these things can be resolved with the best decisions. So I am good. I can say [that] from the depth of my heart, looking straight into the camera.

"When you do things well you can go to bed feeling relaxed. And I sleep well always, always. So I am good, and only thinking about the Champions League final."

The issue is similar to the one that saw Barcelona's Lionel Messi found guilty of tax evasion last summer, with Spain's Supreme Court having recently ratified a sentence of 21 months for the forward, although the punishment was suspended as it was less than two years and he was a first-time offender.