Tanks and armored vehicles are deployed around government buildings and public squares in the Egyptian capital Cairo. Banks, shops and the stock market have suspended business, even though the Islamic weekend has ended.
About 100 protesters in different areas are said to have been killed in clashes with the authorities since last week.
Hundreds of people ignored the curfew on Saturday and held rallies throughout the night to call for President Hosni Mubarak's resignation. They are planning another rally on Sunday afternoon.
Looting disrupted daily life from Saturday to Sunday. Prisoners ran away from a prison near Cairo.
The Egyptian Information Ministry said earlier on Sunday that it had shut down the Cairo branch of Al Jazeera.
The Qatar-based satellite TV network has broadcast detailed reports on the demonstrations in Egypt and the demands made by the protesters.
Observers say the Egyptian authorities closed the Al Jazeera branch as it was afraid the network's coverage would encourage the spread of the demonstrations.