FIFA president Sepp Blatter was shocked by the riots after the Egyptian Premier League match between Al-Masry and Al-Ahly.
More than 70 people were killed after thousands of Al-Masry supporters invaded the pitch to attack rival fans and players.
“I am very shocked and saddened to learn this evening that a large number of football supporters have died or been injured following a match in Port Said, Egypt,” Blatter said on FIFA’s website.
“My thoughts are with the families of those who have lost their lives this evening.”
“This is a black day for football. Such a catastrophic situation is unimaginable and should not happen.”
Egyptian FA president Samir Zaher said the league has been postponed indefinitely as a result of the incident.
Meanwhile, the Confederation of African Football (CAF) has ‘expressed shock’ at the events in Egypt, with president Issa Hayatou sending a message of condolence to the Egyptian FA.
“African football is in a state of mourning,” he said.
A minute’s silence will be held before this weekend’s quarter-final matches of the African Cup of Nations.
Meanwhile, Al-Ahly coach Manuel Jose could leave the club as a result of the violence.
Jose, who is in his second stint in charge of Al-Ahly, has guaranteed that his entire team is safe, but admitted he was a victim of Wednesday’s clashes.
“I am fine, when the game was over I could not return to the locker room because of all the mess,” he told SIC Noticias.
“I was kicked and punched, then I was taken outside the stadium. I saw several fans being given medical attention and many have died.”
“Some of them died inside our locker room, where they had run to. Everyone is fine from our team.”
Questioned about his future at the Egyptian champions, the Portuguese coach said: “Now I will have to think about my life. There are no conditions.”