Hundreds of Egyptian students angered by a mass outbreak of food poisoning at a Cairo university stormed on Tuesday the offices of the country's top Muslim cleric, who presides over the institution.
The Monday outbreak at al-Azhar University forced the hospitalization of 479 students, health ministry official Khaled el-Khateib said.
It occurred after a meal served at the university dormitories in Cairo's Nasr City district.
The university is affiliated with Al-Azhar mosque, the world's foremost seat of Sunni Muslim learning, and awards degrees in sciences and humanities as well as in religious studies.
Ahmed el-Tayeb, the Grand Imam of Al-Azhar whose offices were attacked, is the university's ultimate authority.
Underlining the gravity of the incident, Egypt's top prosecutor ordered an investigation into the outbreak and Islamist President Mohammed Morsi visited one of the several Cairo hospitals to which victims were taken.
Food poisoning is not uncommon in Egyptian university dormitories, where basic hygiene standards are often not observed, but the latest outbreak is the biggest in years.
In Tuesday's protest, thousands of Al-Azhar students blocked the Salah Salem road, a vital artery linking the city's south to its eastern districts.
Some of them broke into el-Tayeb's offices on Salah Salem road near the university's main campus in the medieval part of Cairo.
The students also protested on Monday, blocking roads outside their dormitories and chanting slogans against the university's management.