Agent Jorge Mendes told a Spanish court he has no role in his clients' tax affairs as he gave evidence to a judge investigating a potential €5.6 million fraud during Radamel Falcao's time at Atletico Madrid.
Mendes, who is not accused of any wrongdoing, appeared before Judge Monica Gomez Ferrer for 45 minutes on Tuesday.
Investigators have said they believe some of the agent's clients have used a web of companies in different countries to route image rights income.
On Tuesday, Mendes' Gestifute agency released a statement which said neither he nor any of his staff had any involvement in clients' tax affairs.
"In the statement made by Jorge Mendes before the judge, he clarified that his activity as sports agent, when representing players, is limited solely to representing them in their negotiations with the clubs to determine the salary terms of their contracts," the statement said.
"Neither he nor his employees have ever intervened in the creation of corporate structures for his clients and much less provided any tax advice to them."
The statement added that players "hire their own advisers, unrelated to Mr Mendes."
Last month, a state prosecutor accused Falcao of defrauding Spain's Tax Office of €5.6m from 2012-13.
The alleged unpaid taxes were from money made from endorsement deals through image rights, not from the salary he was then being paid by Atletico. Falcao now plays for Monaco.
Judge Gomez Ferrer is also overseeing the case in which Real Madrid star Cristiano Ronaldo, also a client of Mendes, is due in court on July 31 over an alleged €14.7m tax fraud.
Ronaldo has denied any wrongdoing, with reports suggesting he could leave Madrid and Spain as a result of his anger over the situation.