Cairo: At least 540 students at Egypt’s religious Al Azhar University had suffered food poisoning, reported the health Ministry on Tuesday.

The poisoning was blamed on unhealthy meals that students had eaten at their dormitory in Cairo. The cases angered the university’s students, who on Tuesday held a mass protest and blocked the traffic outside the headquarters of the institution in the suburban Cairo area of Nasr City.

State television reported that President Mohammad Mursi had visited some sick students at a Cairo hospital.

Essam Al Erian, a senior official in the ruling Muslim Brotherhood, said that the mass poisoning was the result of “old corruption” at the university overseen by Al Azhar.

“We look forward to the Grand Shaikh of Al Azhar to take firm decisions and introducing a real change,” wrote Al Erian on his Facebook account.

Al Erian’s comment has raised fears among the liberal-minded opposition that the incident would be used by Islamists to remove the Grand Shaikh of Al Azhar, Ahmad Al Tayyeb, a moderate cleric appointed in the era of the former president Mubarak.

Mustafa Al Najar, a prominent liberal revolutionary, warned in a tweet against “attempts by some people to politicise the issue and hurt the name of Al Azhar and its shaikh”.