Rui Pinto, 30, was detained in Hungary on Jan. 16 on a European arrest warrant issued by Portuguese authorities on suspicion of extortion and secrecy violations.
Pinto's lawyers plan to appeal against the court decision to extradite their client to Portugal for trial.
"Everything I've done was in the public interest because it was necessary to expose and help European authorities understand the criminality that goes on in football," Pinto said in the court hearing which was shown on Portuguese television.
The Football Leaks website includes emails, contracts and presentations relating to soccer clubs.
(Reporting by Catarina Demony,; Editing by Axel Bugge and Ed Osmond)
