Tens of thousands of Egyptians gathered in central Cairo's Tahrir square on Friday, where the country's new prime minister, Essam Sharaf, was expected to address them, dpa reported.
Khairat al-Shater and businessman Hasan Malek, two senior members of the Muslim Brotherhood, will also join protesters in the square - the focal point of regime-toppling demonstrations last month - after they were released from prison Thursday.
Protests continued in Cairo despite the Egyptian Armed Forces' Thursday appointment of Sharaf - replacing the controversial Ahmed Shafiq.
Demonstrators said they were waiting for the rest of their demands to be met, including the release of all political prisoners and the lifting of the state of emergency.
Demands include the dissolution of the State Security Investigations Service and the expansion of the interim period before the presidential and parliamentary elections to a year.
The youth-led April 6 opposition movement said the longer period would allow time to develop stronger political parties that would be able to take part in the elections.
They are also calling for the disbanding of Mubarak's National Democratic Party and the formation of a committee to draft a new constitution for the country.
The Higher Council of the Egyptian Armed Forces suspended the constitution after it took control of the country and promised to hold elections within six months. A judicial committee was formed to oversee amendments of six articles in the constitution.