He argues the constitution offers enough protection to all groups, saying many Egyptians are fed up with street protests that have prevented a return to normality and distracted the government from focusing on the economy.

Rocked by often violent protests in the run up to the two-stage referendum this month, Cairo was calm, with only a small group of protesters burning tires overnight.

Morsi's government says its opponents are damaging the economy by prolonging political upheaval. It has pledged to impose unpopular tax increases and spending cuts to win a loan package from the International Monetary Fund.

Adding to the government's long list of worries, Communications Minister Hany Mahmoud resigned from his post citing his "inability to adapt to the government's working culture".

The United States, which provides billions of dollars a year in military and other support for Egypt and sees it as a pillar of security in the Middle East, called on Egyptian politicians to bridge divisions and all sides to reject violence.

"President Morsi, as the democratically elected leader of Egypt, has a special responsibility to move forward in a way that recognizes the urgent need to bridge divisions," US State Department spokesman Patrick Ventrell said.

Reuters-Xinhua