Egypt's opposition was set to decide on further possible rallies in Cairo on Sunday, after Islamist President Mohamed Morsi announced a key concession in the political crisis dividing the country.
Unrest since Morsi last month announced a presidential decree -- which he repealed overnight -- has killed seven people and wounded hundreds more in clashes between rival Islamist and secular-leaning protesters.
A Morsi aide said that the president had agreed to immediately give up the expanded powers he assumed in the decree, which gave him immunity from judicial oversight.
However, in a meeting with other political figures on Saturday, Morsi said the December 15 referendum on a controversial new constitution drafted by a panel dominated by his Islamist allies would still be held.
Opposition coalition the National Salvation Front was to meet later Sunday to discuss its position, one of its officials told AFP, asking not to be identified.
Cairo's streets remained relatively quiet, meanwhile, with no plans for mass rallies as on preceding days.
But opposition groups were already insisting Morsi's concession did not go far enough.
The April 6 Youth Movement dismissed it as "a political manoeuvre aimed at duping the people," and called for continued protests to stop "the referendum on the constitution of the Muslim Brotherhood."
Prominent opposition leader Mohamed ElBaradei -- a former UN atomic agency chief and a Nobel Peace laureate -- tweeted after Morsi's announcement that "a constitution that curtails our rights and freedoms is a constitution we will topple."
Demonstrators furious at what they saw as a power grab by Morsi and the railroading of the draft constitution have held weeks of street rallies whose demands have escalated into calls for the president's resignation.
On Wednesday, clashes between pro- and anti-Morsi demonstrators outside the presidential palace killed seven people and injured more than 600.
The army stepped in, deploying tanks and troops around the palace. Soldiers reinforced barricades on access roads early on Sunday, piling up concrete blocks three metres (10 feet) high, an AFP correspondent reported.
Air force F-16 warplanes also flew low over the city centre, AFP correspondents reported.
Official news agency MENA said these were exercises to prepare against "hostile air attacks and to secure important state installations," but added that "some saw this as a show of force."
On Saturday, the military issued its first statement since the crisis began, urging the rival camps to talk to stop the situation deteriorating -- "something we will not allow."
Hours later, Morsi's adviser Selim al-Awa announced the president was annulling the November 22 decree, but that the referendum would still go ahead.
Prime Minister Hisham Qandil urged both pro- and anti-Morsi protesters to stop demonstrating and to vote in Saturday's referendum, MENA said.
Qandil said Morsi was constitutionally bound to keep to the December 15 date as the law requires a vote within two weeks of the president receiving the text.
The opposition has consistently demanded that both the decree and the referendum be scrapped before it will begin talks with Morsi.
It rebuffed a Morsi offer on Thursday for talks because he had defiantly defended the decree and said the referendum would proceed, with Egypt having to accept the result.
Opposition figures have denounced the draft charter as weakening protection of human rights and the rights of women and religious minorities.
Those criticisms were echoed by UN human rights chief Navi Pillay. "I believe people are right to be very concerned," she said.
Analysts have said the referendum will probably see the draft constitution adopted, given still strong public support for Morsi and the Brotherhood's organisational skills.
"The Muslim Brotherhood believes that it has majority support so it can win the constitutional referendum," said Eric Trager, analyst at the Washington Institute for Near East Policy.
If that happens, it would "set up the country for prolonged instability."
In Cairo's Tahrir Square, a focal point for hardcore protesters, news of the decree's cancellation sparked no celebrations.
"This will change nothing," said one anti-Morsi activist.