Porto have been formally accused of match-fixing two domestic matches against Estrela da Amadora and Beira Mar during the 2003-04 season.

That year saw arguably Jose Mourinho's greatest triumph as he lead the Portuguese side to the Champions League trophy.

"FC Porto and their president have been notified by the Portuguese Professional Football League (LPFP) of the accusations and investigations," a club statement read

Porto beat Estrela da Amadora 2-0, while the match at Beira ended in a goalless draw, and went on to win the title that year, beating Benifica by eight points.

The case - referred to in Portugal as "the golden whistle" - has been monitored for nearly four years, with close collaboration between the LPFP and the Portuguese legal system.

Porto have sent the accusations to their lawyers and have five days to submit their defence, although it is not thought Mourinho is likely to face charges.

The club could be docked three points from this campaign - in which they currently lead Benfica by 16 points - or face relegation to the second division.

Jorge Pinto da Costa, the club president, could also face a ban of between two to 10 years if found guilty of corruption or six months to two years for attempted corruption.

Da Costa is to go to trial in a civil lawsuit by Porto prosecutors after he was accused of bribing the referee of the Beira Mar v Porto game.