The background to this is a concerted attempt by public prosecutors in Spain to target high-earners suspected of tax evasion, with Jose Mourinho and Cristiano Ronaldo the most recent big names implicated, although both have strongly denied any wrongdoing.
Other clients of Mendes who have ended up in Spain include the Portuguese full-back Fabio Coentrao - on the verge of joining Sporting Lisbon on loan from Real Madrid - and Colombian striker Radamel Falcao, now with Monaco but formerly at Atletico Madrid.
However, a statement by his agency Gestifute read: 'Jose Mourinho has not received any notification with regards to the news published today.
It added that Mourinho paid "more than 26 million euros in taxes, with an average tax rate over 41 percent, and accepted the regularization proposals made by the Spanish tax authorities in 2015 regarding the years of 2011 and 2012 and entered into a settlement agreement regarding 2013".
The prosecutor said last Tuesday that there was evidence that Ronaldo used a shell company in the Virgin Islands to hide the money he made from image rights.
Real Madrid star Ronaldo was last week accused of evading €14.7 million through offshore companies and will appear before a judge on July 31, judicial sources said.
Paris Saint-Germain player Angel Di Maria, who admitted to tax fraud during his time with Real Madrid, has been handed a one-year jail term and will pay a £1.76million fine.
Prosecutors claim that the Portuguese manager - who took over at Manchester United in 2016 - failed to declare income of €1.6 million in 2011 and €1.7 million in 2012.
However, Di Maria is unlikely to serve time behind bars as a sentence under two years for non-violent crime can be served as probation, according to the Spanish law.
Former Barca defender Javier Mascherano also agreed a one-year suspended sentence with authorities for tax fraud last year.