The prosecutor said Ronaldo used shell company in the Virgin Islands to cheat on his taxes. Mourinho, 54, allegedly owes the Spanish tax authorities €3.3 million ($3.7 million).
It has been claimed that the Portuguese superstar is angry with the tax fraud allegations that a federal prosecutor in Spain has brought forward against him in the country.
Since 2013, Mourinho has spent the past four years managing British football clubs - Chelsea from 2013 to 2015 and then Manchester United since 2016. He now is the coach of English club Manchester United.
Ronaldo, who played under Mourinho at the Bernabeu, has denied the charges and is threatening to leave Spain. Real Madrid and Man United are not directly involved.
In his 2011 and 2012 tax returns, he is alleged to have failed to declare earnings from his image rights, which prosecutors say he did "with the intention of obtaining illegal benefit".
A request for comment from Mendes' agency, Gestifute, was not immediately answered.
It will now be up to a judge to decide whether to take Mourinho to court.
Earlier this year Barcelona star Lionel Messi had a suspended 21-month jail sentence for tax evasion upheld by the Spanish Supreme Court. Messi and his father, Jorge, were found guilty on three counts of defrauding the tax department to the tune of about £3.5million.
Mourinho accused of 3.3mn euro tax fraud in Spain
Perez is hopeful Ronaldo will stay, but has set the asking price at £1bn nonetheless, just to scare off any interested parties. Portuguese sports daily A Bola had also claimed that Perez had already been informed of the 32-year-old's decision.
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