Rival mass protests have been called for next Tuesday in Egypt, over a bitterly disputed constitutional referendum, raising the potential for more violent street clashes in a sharpening political crisis.
AFP reported that President Mohammed Morsi's chief foes, the opposition National Salvation Front, called on Sunday for huge protests in Cairo to reject the December 15 referendum on a new charter.
The Muslim Brotherhood, from which Morsi hails, told AFP that it and allied Islamist movements would counter with their own big rallies in the capital in support of the referendum.
If the dueling demonstrations go ahead, there is a risk of vicious further clashes like the ones that erupted between both sides outside the presidential palace last Wednesday, killing seven people and wounding hundreds.
Egypt's army, which is trying to remain neutral in the deepening struggle, warned on the weekend it "will not allow" a worsening of the crisis. It said both sides must start dialogue.
Morsi has made a key concession to the opposition on the weekend by rescinding a decree giving himself wide-ranging powers free from judicial challenge.
The opposition was unmoved and maintained its position that no talks could happen while the referendum was going ahead.
"The Front calls for demonstrations in the capital and in the regions on Tuesday as a rejection of the president's decision that goes against our legitimate demands," National Salvation Front spokesman Sameh Ashour told a news conference, according to AFP.
"We do not recognize the draft constitution because it does not represent the Egyptian people," he said, reading a statement.
Going ahead with the referendum "in this explosive situation with the threat of the Brothers' militias amounts to the regime abandoning its responsibilities," he said.
The Brotherhood's spokesman, Mahmud Ghozlan, told AFP that the Alliance of Islamist Forces it belongs to was also "calling for a demonstration Tuesday, under the slogan 'Yes to legitimacy'," and in support of the referendum.
The almost nightly protests over the past two weeks have brought out thousands of people into the streets.
In recent days, the protesters have hardened their slogans, going beyond criticism of the decree and the referendum to demand Morsi's ouster.
Amid the protests and tensions, the army was watching nervously. Tanks and troops have been deployed outside the presidential palace but they have made no move to confront the demonstrators.
On Sunday, air force F-16 warplanes flew low over the city center. The official MENA news agency described the unusually low flyover as an exercise against "hostile air attacks and to secure important state installations."
That did not prevent several hundred anti-Morsi protesters gathering outside his palace late Sunday, AFP reported.