By Hadeel Al Shalchi
CAIRO (Reuters) - Egyptian police fired teargas at protesting students at Cairo's al-Azhar university on Wednesday hours after authorities announced the detention of Muslim Brotherhood leader Essam El-Erian, part of a crackdown against the Islamist movement.
Erian, deputy leader of the Brotherhood's Freedom and Justice party, was taken into custody from a residence in New Cairo where he had been in hiding, an Interior Ministry source told Reuters.
At the al-Azhar university's main campus, students smashed windows, hurled chairs and covered 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 President Mohamed Mursi.
One police officer yelled: "Arrest anyone you see. Bring me those kids. If you see anyone just arrest them right away."
Students at Egypt's top institution for Islamic teachings have demonstrated for weeks in support of the Islamist Mursi, whom the army toppled in July after mass protests against his rule. Demonstrations there are a sensitive matter because the institution has historically toed the government line.
Many Brotherhood leaders have been detained since the overthrow of Mursi, Egypt's first freely elected president. He, Erian and 13 other Brotherhood leaders are expected to go on trial on Monday on charges of inciting violence.
The charges relate to the deaths of about a dozen people in clashes outside the presidential palace last December after Mursi enraged protesters with a decree expanding his powers.
The trial of three senior Muslim Brotherhood leaders on charges of inciting violence was halted on Tuesday after the judge withdrew from the case for unexplained reasons.
The trials are likely to create more upheaval in Egypt, which has a peace treaty with Israel and controls the Suez Canal, a vital global trade route.
TURMOIL IN STRATEGIC NATION
The Brotherhood, which demands Mursi's reinstatement, accuses the army of staging a coup that sabotaged democratic gains made since a popular uprising toppled autocrat Hosni Mubarak in 2011.
At least 1,000 people, including members of the security forces, were killed in the violence that followed Mursi's overthrow. Hundreds of his supporters died when police forces stormed two protest camps on August 14.
An Egyptian court in September banned the Muslim Brotherhood group and seized their funds to try to crush the movement, which the government accuses of inciting violence and terrorism.
The Brotherhood's discipline and hierarchy helped it win elections after the revolt that toppled Mubarak, eventually propelling Mursi into power.
Now the army-led government and its supporters regard the Brotherhood as a terrorist group and enemy of the state. The security forces and police, feared and despised under Mubarak, are lauded for cracking down on the organisation.
The Brotherhood says it is committed to peaceful protest. Although it has said it will carry on with them until the army-backed government falls, the demonstrations are smaller and shorter than ones staged when Mursi was first deposed.
Islamists appear to have adopted a policy of choosing sensitive sites like Al-Azhar to air their views instead of taking to the streets in big numbers.
Critics of the government - which has announced a road map leading to new elections - say it is becoming more authoritarian, stifling dissent and limiting freedom of speech.
Human rights groups and some liberal politicians have expressed alarm over a draft law under debate that would place severe restrictions on protests.
New York-based Human Rights Watch said the law would give police carte blanche to ban protests or forcibly disperse them, said Sarah Leah Whitson, HRW'S Middle East director.
"The final law will be an important indicator of the extent to which the new government is going to allow for political space in Egypt." (Reporting by Asma Alsharif and Omar Fahmy; Editing by Michael Georgy and Angus MacSwan)