Egyptian police entered Al-Azhar University in Cairo on Wednesday to confront Islamist protesters, the first time security forces have moved on a campus since a 2010 court ruling.
The police took the action at the prestigious Islamic university following a request from its administration, the interior ministry said.
Students supporting deposed Islamist president Mohamed Morsi have held regular and sometimes violent protests since the beginning of the school year in September.
According to the official MENA news agency, the protesting students had stormed the university's offices on Wednesday, ransacking them and firing birdshot.
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Police entered "the Al-Azhar University campus following a request from the university's head Dr Osama al-Abd to defend lives and public property," said the interior ministry.
The police had obtained permission from the state prosecutor before doing so, it added in a statement.
A police general told AFP it was the first time police had entered a university since a 2010 court ruling banned guards belonging to the interior ministry from operating on their grounds.
Pressed by police at every turn, Islamists have adopted universities as protest hubs to galvanise their flagging movement four months after the military overthrew Morsi.