Update at 11:55 a.m. ET: Hundreds of thousands of protesters swelled Cairo's Tahrir square to defy a curfew and press demands that President Hosni Mubarak step down

The U.S. Embassy, meanwhile, confirms that U.S. Ambassador to Cairo Margaret Scobey spoke with opposition leader Mohamed ElBaradei.

In interviews, the Nobel laureate ruled out talks with the government saying first that Mubarak "must leave to avoid bloodshed."

As night fell on Cairo, AlJazeera reports that more than a million people had jammed into the Egyptian capital to keep up the week-long anti-government pressure. Hundreds of thousands of protesters also gathered in Alexandria and Suez.

Update at 9:56 a.m. ET: The U.S. State Department has ordered non-essential U.S. government personnel and their families to leave the country amid the growing anti-government protests and uncertainty over the security situation.

It said it had taken the step "in light of recent events," the Associated Press reports.

Earlier posting: ElBaradei, a Nobel laureate, tells the broadcaster al-Arabiya, "We are already discussing the post-Mubarak era," Reuters reports.

"There can be dialog, but it has to come after the demands of the people are met, and the first of those is that President Mubarak leaves," he says.

"I hope to see Egypt peaceful, and that's going to require as a first step the departure of President Mubarak. If President Mubarak leaves, then everything will progress correctly," he says.

Muslim Brotherhoood leader Abdel Moneim Aboul Fotquh says the opposition refuses to negotiate with Mubarak or his government.

"Our first job is to see Mubarak step down," he tells Al-Jazeera TV. He says Mubarak is the one responsible for the "catastrophe" in Egypt.

Turkish Prime Minister Tayyip Erdogan calls on the Egyptian president to meet the "freedom demands" of protesters. Erdogan postponed his planned trip to Cairo next week until "the situation returns to normal," the AP reports.

"Listen to people's outcries and extremely humanistic demands," Erdogan says today in a televised address to members of the ruling AK Party, Reuters reports. "Meet the freedom demands of people without a doubt."

ElBaradei seen as a temporary leader. Key Muslim groups support protest.

Update at 6:52 a.m. ET: Hundreds of thousands of protesters are packing Cairo's Tahrir Square in the largest challenge to the embattled regime of President Hosni Mubarak in a week of demonstrations, USA TODAY's Jim Michaels and Theodore May report.

Al-Jazeera TV estimates the crowd in the square at near 1 million. The network reports that tens of thousands of protesters are being held on nearby Kasr Al Nile bridge nearby and that roads into the heart of the city have been blocked.

Soldiers ring the square but are letting protesters pass after checking them for IDs and weapons.

The demonstration is under tight army security, but both sides have avoided confrontations. The army has pledged not to use force against demonstrators as long as they are non-violent.

There is almost a carnival atmosphere in the square, with some people painting their face in the red, white and black national colors. Many fathers have hoisted their children on their shoulders.

The protesters insist that Mubarak step down and have rejected his efforts to call on his vice president to open talks with other parties.

"If he doesn't leave, the protest will go on until he does," says Wael Abu Halawa, 35, an imam who joined the protest this morning.

At the center of the protest are two effigies of Mubarak hanging from a traffic signal. One has the Star of David painted on the chest.

The crowds remain in a positive mood as people pack into the square under sunny skies.

Other Egyptians watching from the balconies around the square toss dates and bottles of water to the crowds that flow by chanting, ""We're not going. He needs to go!"

Earlier posting: Tens of thousands of protesters have gathered in Cairo's Tahrir Square, and thousands more are streaming into the area past soldiers who have formed a human chain to check demonstrators for IDs and weapons as they enter, Al-Jazeera reports.

The crowds have gathered despite a cutoff of phone lines, Internet and train service in an attempt by authorities to thwart the protesters.

Tanks have been positioned near the square, Al-Jazeera reports, but the military has maintained its non-aggressive posture. The armed forces pledged in a statement on national TV on Monday not to use force against protesters exercising their "legitimate" rights as long as they are non-violent.

A military spokesman said the military "has not and will not use force against the public" and underlined that "the freedom of peaceful expression is guaranteed for everyone," the Associated Press reports.

Mubarak has rejected the protesters' demands and instead named a vice president, Omar Suleiman, and ordered him to open talks with other parties and factions.

Protesters demand the ouster of President Hosni Mubarak. Al-Jazeera TV says the crowds will go from the square toward the presidential palace today.