CAIRO — Opposition leader Mohammed ElBaradei emerged from house arrest Sunday evening to join tens of thousands of protesters in central Cairo, calling on President Hosni Mubarak to resign and perhaps establishing himself as the face of Egypt’s six-day pro-democracy uprising.

“Today, each of us is a different Egyptian,” ElBaradei, the Nobel laureate and former head of the U.N. nuclear watchdog agency, said through a megaphone in jam-packed Tahrir Square. “We have restored our rights, we have restored our freedoms. What have begun cannot be reversed…

“We have a key demand: for the regime to step down and to start a new era.”

The nighttime appearance by ElBaradei, who had been placed under house arrest when the protests exploded into violence on Friday, came amid throngs of protesters who again ignored a nationwide curfew imposed by Mubarak, the U.S.-allied dictator who’s struggling to maintain his nearly three-decade grip on the Arab world’s most populous nation.

In Washington, Secretary of State Hillary Clinton called on the 82-year-old Mubarak to make a “peaceful, orderly transition to greater democracy,” but she again stopped short of saying that he should step down.

Mubarak showed no obvious signs that he was giving up. News services reported that the Egyptian army was sending reinforcements to various parts of Cairo, and state television said that the police, who have been absent from the streets since Friday, would resume patrols.

Earlier Sunday, authorities shut down the Al Jazeera news channel’s Cairo bureau — which has provided the world with a front-row seat to the revolt with live broadcasts from Tahrir, or “Liberation,” Square — and fighter jets buzzed the square in an ominous show of military force.

On Saturday, Mubarak named former intelligence chief Omar Suleiman as his first-ever vice president and Ahmed Shafiq, a former air force chief of staff, as the new prime minister, fueling speculation that Mubarak was preparing to hand over power to his closest allies. The news has done nothing to deter the protestors.

Speaking on CNN, Clinton said, “What we’re trying to do is to help clear the air so that those who remain in power, starting with President Mubarak, with his new vice president, with the new prime minister, will begin a process of reaching out, of creating a dialogue that will bring in peaceful activists and representatives of civil society to … plan a way forward that will meet the legitimate grievances of the Egyptian people.”

Clinton’s remarks showed that the Obama administration understands that Mubarak’s days are numbered and the decision on a successor government lies with the Egyptian people, said Nader Hashemi of the University of Denver’s Josef Korbel School of International Studies.

“There seems to be a shift in U.S. policy where the Egyptian people are given respect and their right to determine their future is finally being acknowledged by the American government,” he said.

News reports said that dozens of prisoners had escaped from jails and residents were arming themselves to defend overnight against gangs of looters and vandals that many Egyptians believe have been unleashed by the hated Interior Ministry to sow chaos.

Earlier Sunday there was almost no police presence on the streets, and military tanks stayed parked in Tahrir Square and other key neighborhoods without confronting protestors who were defying a curfew that began at 4 p.m. local time, or 8 a.m. Eastern time.

As dusk fell over Cairo, two army tanks rolled through a residential neighborhood in Dokki, a middle-class western suburb where residents had armed themselves with kitchen knives the night before to guard against the gangs. The residents welcomed the tanks.

The death toll in the week of protests was at least 150, according to Al Jazeera, the pan-Arab channel whose live broadcasts of Tahrir Square have provided the world with a front-row seat to the revolt.

On Sunday morning, the official Mena news agency reported that the government had ordered Al Jazeera to suspend its operations and was revoking its license to broadcast from the country. The channel continued to report and to broadcast images via a satellite connection, however.

(Allam reported from Cairo, Bengali from Baghdad.)