Riot police were stationed outside several key buildings in the area and a number of arrests have been made.

Several protesters were badly injured

Running battles continued throughout the day between students and police with riot shields.

Al-Azhar University - the scene of the protest - is the most prestigious institution for mainstream Sunni Muslims, attracting students from around the world.

The students, shouting religious slogans, pelted police with stones from behind the fence of the university buildings.

Cars, paving stones

The police shot back with teargas and rubber bullets as the protests grew increasingly violent.

"Oh Islam, we will sacrifice our blood and soul for you," the students shouted.

Some of the students, shouting "There is no God but Allah", ripped up paving stones to try to block a main road.

Ten cars and two buses were reportedly damaged in the exchanges.

One account said a police officer was stoned by the students.

A BBC correspondent at the scene said the clashes were believed to be the worst in Cairo since the protests against the Gulf War in 1991.

Riot police protect the university

The book that triggered this protest, first published in Beirut in 1983, was released in Egypt in November by an institution affiliated with the Culture Ministry.

On Friday, the ministry appointed a committee to assess the complaints against the book, and promised to publish the results.

However one protester, who had not read the book, was unsatisfied: he said that everyone responsible for it deserved to die.

He said that if the Minister of Culture, Farouq Hosni, did not resign, he should be assassinated.