At least nine demonstrators have been killed and 361 others wounded since the clashes began Friday, the Health Ministry said.
Television footage showed military police beating protesters with sticks as they cleared the Cairo square, the epicenter of the popular uprising that toppled President Hosni Mubarak in February.
The violence reflects growing tension between the military council that took over after Mubarak’s fall and the young activists who helped drive him from power, even as the country holds parliamentary elections that have been dominated by Islamists.
The clashes began when military police broke up a protest encampment outside the Cabinet building following scuffles with demonstrators who were enraged about the arrest and beating of an activist. The troops withdrew late Friday afternoon, but confrontations continued overnight.
On Saturday, military police returned to disperse the crowds still in the streets, chasing them toward Tahrir Square.
Television footage showed both sides hurling rocks at each other, and protesters tossing gasoline bombs at government buildings during running street battles.
Demonstrators said the violence brought back memories of how authorities confronted dissidents under Mubarak.
"They were beating and humiliating everyone they put their hands on," said Nader Saied, a 30-year-old protester. "Even youngsters, elders and kids were not excluded. It just shows that nothing has changed after the revolution. Everything is still the same, if not even worse."
The Muslim Brotherhood, whose Freedom and Justice Party appears to have a commanding lead in the first two rounds of the election, Friday expressed its "utter shock and dismay at the sight of the army killing and wounding people in large numbers."
Prime Minister Kamal Ganzouri, whose recent appointment was one of the protesters’ chief complaints, accused protesters of attacking the Cabinet building.
"There are certain quarters who don’t want the stable security that started a few days ago to continue," he said at a news conference Saturday. "What is happening now is not a revolution but an assault on the revolution."
-- Amro Hassan
Photo: An Egyptian protester uses a slingshot against soldiers, unseen, as a building burns during clashes near Tahrir Square on Saturday. Credit: Ahmad Hammad/Associated Press