CAIRO - The Fédération Internationale de Football Association (FIFA), the world governing body of soccer, said that it is not permitted to alter the Egyptian players' contracts with their clubs after the calling off of the Egyptian Premier league last week, Egypt's official Middle East News Agency (MENA) reported. A letter from FIFA to EFA stressed that the clubs must pay the players' dues on time, according to their existing contracts. The EFA Executive Committee, headed by Anwar Saleh, decided last week to cancel the Premier League 2011-12 season, holding instead a friendly tournament called ‘The Martyrs' Cup'. On February 1, in the coastal city of Port Said, a match between Al-Masry and Al-Ahly in the Egyptian Premier League turned violent, claiming the lives of at least 74 Al-Ahly fans and injuring around 1,000 more. Seconds after the final whistle, thousands of supporters of Port Said team Al-Masry invaded the pitch, hurling bottles and rocks at the fans of Cairo's Al-Ahly. Last Thursday, Egypt's Prosecutor-General referred 75 people to the criminal court, charged with premeditated murder, in the wake of the violence. The FIFA letter came in response to an EFA letter, upon the request of the clubs, asking Egyptian clubs to be allowed to alter their players' contracts in the wake of the cancelling of the Premier League. The Egyptian Premier League was postponed and then cancelled, while most soccer clubs have suspended all their sporting activities and declared 40 days of mourning. The temporary committee that now leads EFA is headed by Saleh, after the previous board members resigned after the Port Said tragedy early last month. FIFA, founded in 1904, added that any clubs that changes its players' contracts will be severely punished, urging EFA to mediate in favour of keeping and maintaining the players' contracts as they are until further notice.