The menace was a counterpoint to Tahrir Square, where the literati and well-off demonstrators mixed with the poorest of rough-and-tumble neighborhoods in scenes of camaraderie and determination that have made the square an emblem of the revolt. Protesters flashed V-for-victory signs at dawn, celebrating their success in holding the square and even pushing the barricades forward in clashes that dragged through the night.

Protesters accused government supporters of trying to block them from delivering supplies to the square, but boxes of water, bananas, yogurt and medicine still made it in. The Internet was working. Volunteers swept the streets, pushing piles of rocks to the curb that looked like bluffs of snow. Doctors staffed first-aid clinics, near graffiti that read, “We are writing the history of a free Egypt,” and men frisked people entering for weapons.

“Don’t incite them!” shouted Mahmoud Haqiqi, holding aloft a sign that read, “No to shedding of blood.” But even those who lamented the turn to violence blamed Mr. Mubarak’s supporters for provoking them and vowed not to relinquish the square. “Right now, it’s all here, protecting Tahrir Square,” said Hisham Kassem, a veteran activist and publisher, who kept a wary eye on barricades built with corrugated tin, wrecked cars and trucks, barrels, buckets filed with sand and metal railing torn from the curb. “We keep it tonight, and tomorrow the whole country is going to come out.”

He surveyed the crowd and shook his head. “I can’t face the idea of this failing.”

For days, the government seemed to stagger at the scale of an uprising that overwhelmed Egypt’s once ubiquitous security forces on Friday. The concessions on Thursday marked its most concerted attempt to address at least some of the longstanding demands in a country that many believe has stagnated under Mr. Mubarak’s rule. The newly appointed prime minister, Ahmed Shafiq, apologized for the violence and vowed to investigate who instigated it. Mr. Suleiman followed with a lengthy television interview in which he recognized what he described as “the revolution of the youth.”

Mr. Suleiman sought to project an image of good will, offering dialogue with the Muslim Brotherhood, which remains banned, even though it is the country’s most influential opposition group. In a sign of the new landscape, Mr. Suleiman referred to it by name rather than the government’s usual coded language, though he and Mr. Mubarak have both suggested it was behind the revolt. Its followers have played a forceful role in the protests, but its leaders have, so far, tried to remain in the background.

“We have contacted the Muslim Brotherhood and invited them, but they are still hesitant about the dialogue,” he said. “I think that their interest is to attend the dialogue.”

Other concessions came from Egypt’s public prosecutor, who issued a travel ban on former government ministers and an official of the ruling National Democratic Party on suspicion of theft of public money, profiteering and fraud, state television reported. Among the four was the hated former interior minister, Habib el-Adly, who commanded a police force that was widely despised for its corruption and routine use of torture.