EGYPTIAN security forces have fired tear gas to disperse students protesting outside Cairo University in support of the country's ousted Islamist president as unrest spread to a second college campus in the capital.

Across the capital, students at the Islamic Al-Azhar University in eastern Cairo have clashed sporadically with police since Sunday as they rally in support of 20 of their peers who have been arrested and charged for protesting against the military-backed authorities.

Since the military removed President Mohammed Morsi from power in early July, Egypt's security forces have conducted a relentless crackdown against the ousted leader's Muslim Brotherhood.

This has resulted in the killing more than 1000 of the fundamentalist group's supporters and rounding up most of its leaders.

Universities — where the Brotherhood has long enjoyed a strong presence — have emerged as a key battleground in Egypt's political turmoil.

A day after violence and arrests at Al-Azhar University, students at Cairo University yesterday clashed with security forces after trying to march towards a large intersection that links the school's grounds with a bustling commercial neighbourhood.

A security official said students lobbed plastic bags filled with water at security forces.

Hazem Tarek, a student leader at Cairo University, said hundreds of students went out to support their colleagues at Al-Azhar University, and were met with tear gas from the police, and at least four students were wounded by shotgun pellets.