Security officials say police backed by armored vehicles have stormed the campuses of at least two prominent Egyptian universities to quell anti-government protests by students.

Sunday's largest rallies took place at Cairo and the Islamist al-Azhar universities. They were organized by supporters of ousted Islamist President Mohammed Morsi.

Student protest spokesman Youssef Salhen said protesters clashed briefly with police outside al-Azhar.

A security official said at least six people were arrested at al-Azhar, where police fired tear gas. He spoke anonymously because he wasn't authorized to speak to the media.

Authorities have intensified security at universities nationwide to prevent the resurgence of student protests. Last year, at least 16 students were killed.

Morsi's supporters continue to hold small, scattered protests despite a crackdown after he was ousted in July 2013.