It's now nearly 48 hours after the football match in Port Said that ended in perhaps one of the most significant tragedies of recent times.

74 fans were killed following al-Masry's unexpected win over al-Ahly, Egypt's most famous and successful club.

What happened is now pretty clear. After the final whistle, al-Masry's fans invaded the pitch, seeking to attack al-Ahly's players; after that, they charged into the al-Ahly fans. Dozens of people were crushed to death, suffocated or fatally stabbed.

But why this happened - and who is to blame - is now the major talking point. As the BBC's Yolande Knell explains:

Did fans instigate the clashes themselves, was there a conspiracy to provoke, was there deliberate negligence by police? Or was the whole thing just a case of badly trained police mishandling football crowd violence. These are now politically charged questions.

World Have Your Say will be on BBC World television at 1500 GMT discussing this question.