Pinto, who has been held since returning to Portugal in March, hacked millions of files and has been charged with "aggravated attempted extortion" and data theft. He could face 10 years in prison.
"The undersigned lawyers denounce the incredible judicial harassment of their client, Mr. Rui Pinto," wrote William Bourdon, who is French, and Francisco Teixeira Da Mota, who is Portuguese.
"Detention is disproportionate to facts that are unlikely to be classified as criminal," they wrote.
The Portuguese authorities suspect Pinto accessed the computer systems of the Portuguese state, the Sporting Lisbon football club and the investment fund Doyen Sports and then published confidential documents on a website.
The hacker then asked Doyen for money to hush up compromising documents, but has said this was part of his attempt to show the dishonesty in football.
Pinto, who had been living in Hungary since 2015, was extradited to Portugal on March 21.
According to his lawyers, Pinto is the victim of an alliance of clubs, agents and others in the football business and his continued detention "is the result of the mobilisation of all those in Portugal worried about their judicial responsibility for the financial crimes revealed by Football Leaks".
They also criticise "the Portuguese media, fed by a judiciary".
Last week, Portuguese weekly Sabado reported that the prosecutor's office wanted to broaden the scope of the investigation and extend the detention of Pinto, who is also suspected of having access to email accounts at the Public Prosecutor's Office and the Portuguese Ministry of the Interior.
His lawyers have argued that Pinto is a "very important European whistleblower" who has made possible investigations in several countries into wrongdoing in football.