Egypt gave the army sweeping authority to arrest and detain civilians on Monday, as clashes continued in cities around the country.
A cabinet member told Reuters the powers had been granted in response to unrest over the past three days, which has claimed 50 lives and injured hundreds.
President Mohammed Morsi was due to hold talks with 11 opposition political parties on Monday evening in a bid to end the violence that has swept the country since the second anniversary of the revolution that overthrew Hosni Mubarak in 2011.
The talks follow reports that leftist opposition groups were planning to meet on Monday.
The government imposed a curfew in Port Said and other areas that had been hit by riots on Sunday. But large protests were reported in Port Said and other cities despite the ban on public gatherings. Protestors also reportedly marched on Parliament in Cairo on Monday afternoon.

The Egyptian army has been given powers of arrest not seen since the state of emergency was lifted last year.