Egyptian President Mohamed Morsi had annulled a decree that granted him expansive power and the army was mobilized to maintain security, officials said.
But Morsi took no action on a demand he postpone the referendum set for Saturday that would allow an overhaul of a draft constitution, which critics say has little protection of individual rights and would give Islamic leaders more influence, The New York Times reported.
In a televised statement on al-Arabiya, Vice President Mahmoud Mekki said the army had been mobilized to maintain security. The Egyptian cabinet approved measures permitting the army to use force if "necessary to perform their duty," Al-Ahram newspaper reported.
Islamist politician Mohammed Selim el-Awa told a news conference Saturday the referendum on a draft constitution on Dec.15 would go ahead as planned and be immune from judicial appeal, al-Masry al-Youm said.
"If the people voted no to the referendum, a new Constituent Assembly will be formed within three months via general elections, after which it will write a new constitution within six months," he said
However, one of the key demands of Morsi's opponents was to halt the referendum.
Ahmed Said, head of the Free Egyptians Party and a key member of the National Salvation Front coalition, called Morsi's announcement shocking, saying it failed to halt the referendum, the BBC said. Former presidential candidate Mohamed ElBaradei, one of the founders of the National Salvation Front, called Morsi's decision " arm-twisting." The party was due to issue a response later Sunday.
Tanks, concrete blocks and barbed wire surrounded Morsi's palace in Cairo, which has been the flashpoint of violence in the country in the past week, the BBC said.
At least seven people were killed and hundreds injured in violent protests between anti-Morsi protesters and supporters that plagued the country after Morsi announced a decree giving him sweeping powers shielding him from judicial review, Ahram Online said.