Egyptian President Mohammed Morsi has declared a state of emergency in the cities of Port Said, Suez and Ismalia after days of deadly unrest.
At least 33 people died over the weekend in Port Said, where a court judgement sparked rioting, and discontent with Mr Morsi's rule fuelled unrest elsewhere, the BBC reports.
In the capital Cairo, anti-government protesters clashed with security forces near Tahrir Square for a fourth consecutive day.
In a televised speech to the nation Mr Morsi said a daily curfew from 9pm to 6am will be imposed for 30 days from Monday.
Mr Morsi said he mighty take further steps "for the sake of Egypt" as it was his "duty" as president.
"I have said I am against any emergency measures but I have said that if I must stop bloodshed and protect the people then I will act," the president said.
The state of emergency applies to the three cities along the Suez Canal, and their surrounding regions.
The liberal opposition accuses Mr Morsi of being autocratic and driving through a new constitution that does not protect adequately freedom of expression or religion. The government is also being blamed for a deepening economic crisis.
Mr Morsi also invited political leaders to a "national dialogue".