Egyptian Vice President Omar Suleiman has rejected calls for the immediate resignation of President Hosni Mubarak, saying the move would be a "call to chaos."
His comments came as rock-throwing protesters defied curfew in the capital, Cairo, where sporadic gunfire was heard on the streets into the night.
Protesters who oppose Mr. Mubarak's decision to remain in office until the end of his term have pledged to launch another mass demonstration Friday as they press for the president's immediate departure.
Mr. Suleiman said in an interview on state television that the president was putting together a "road map" to address the demands of protesters. The vice president also said he had begun holding talks with representatives of youth and opposition groups.
However, Mr. Suleiman said the Muslim Brotherhood - Egypt's largest opposition group - was "hesitant" about participating in dialogue. He confirmed earlier reports that President Mubarak's son, Gamal, will not run for president.
The vice president described clashes in Cairo between government supporters and opponents as a "conspiracy." Mr. Suleiman said the government was not involved but would find those responsible.
Earlier Thursday, Egyptian soldiers took positions between pro- and anti-government protesters in Cairo, where gunfire had erupted earlier in the day. Several tanks were stationed near Cairo's Tahrir Square as thousands of anti-government protesters gathered there and built barricades.
One of the tanks stood on a highway overpass, where earlier Thursday, supporters of President Mubarak had been throwing rocks at anti-government protesters below.
Also Thursday, Prime Minister Ahmed Shafiq apologized for violent clashes that broke out Wednesday when supporters of Mr. Mubarak surged into Tahrir Square and faced off against opposition demonstrators. He called the incident a "disaster" and said it would not happen again.
Some information for this report was provided by AP, AFP and Reuters.