Egyptian opposition protesters are gathering in Cairo's Tahrir Square to mark the second anniversary of the uprising that toppled Hosni Mubarak's autocratic regime.

The protesters, mostly led by liberals and secularists, are using the anniversary to stage a show of strength in a bid to force President Mohammed Morsi to amend a disputed constitution drafted by his Islamist allies. They are also demanding freedom of expression and the independence of the judiciary.

Hundreds of thousands are expected to turn out for the rallies planned in Cairo and several major cities. Morsi's Muslim Brotherhood and other Islamist groups are staying off the streets to avoid clashes.

Friday's rallies come a day after opposition protesters battled police for hours near Tahrir. The clashes injured scores of opposition protesters.