Egyptian police fired teargas at students protesting at Cairo's al-Azhar university hours after authorities announced the detention of Muslim Brotherhood leader Essam El-Erian, part of a crackdown against the Islamist movement

Students at the country's top institution for Islamic teachings have been demonstrating for weeks in support of ousted President Mohamed Morsi, who the army toppled in July after mass protests against his rule.

At al-Azhar's main campus, students smashed windows, hurled chairs and covered the walls of an administrative building with graffiti.

"Sisi is a dog. Down, down with the lord of the army," one protester scribbled, refering to army chief General Abdel Fattah al-Sisi, who led the overthrow of Morsi.

One police officer yelled: "Arrest anyone you see. Bring me those kids. If you see anyone just arrest them right away."

Mustafa el-Agrawi, al-Azhar's legal adviser, told the ONTV private channel that the students besieged the administrative building, locking up the university chief and several other administrators.

Ahmed Hosni, deputy head of al-Azhar, said the students stormed the offices, trashed documents and computers to "sabotage and destroy the university". The head of al-Azhar university had called on the police to enter campus grounds to "protect souls and properties", according to an interior ministry statement.

Senior Muslim Brotherhood figure Essam al-Erian was arrested on Wednesday. [AFP /HO/EGYPTIAN INTERIOR MINISTRY]

Erian arrest

Erian, the deputy leader of the Brotherhood's Freedom and Justice party, was taken into custody early on Wednesday from a residence in New Cairo where he had been in hiding.

"He's been arrested and details will soon be released," an Interior Ministry source told Reuters news agency.

Local media circulated a photo of what they described as the moment he was arrested, showing a smiling Erian standing next to a bed with two packed duffle bags.

Many Brotherhood leaders have been detained since the army deposed Morsi, Egypt's first freely elected president, and declared a road map leading to elections.

Source: Agencies