Egypt's public prosecutor on Thursday ordered the release of 100 students arrested over violence-related charges since the ouster of Islamist president Mohamed Morsi, ahead of the fourth anniversary of 2011 popular uprising.

The prosecutor's office said in a statement that the move came amid a thorough review of previous detention decisions, and coincides with the anniversary of the popular revolt that toppled long-time autocrat Hosni Mubarak.

It added that the decision to let the detainees walk free was out of "concern for their academic future."

The students have not been formally charged.

Since the ouster of Morsi last year, universities have been a hub of opposition demonstrations against the new authorities, against the backdrop of a state crackdown on Islamist supporters of Morsi.

Hundreds of students have since been expelled from their respective universities, jailed or handed prison terms.

Thursday's decision came hours after a court ordered the release of the two sons of Mubarak pending retrial in a corruption case.

The announcement was not the first time the prosecutor has ordered the release of students.