Egypt's embattled President Hosni Mubarak appeared on television early on Saturday for the first time since country-wide protests erupted four days ago, refusing to accede to popular demands that he resign.

Mubrarak announced that he would dismiss the Egyptian government and see to appointing a new government on Saturday. He defended the security forces' crackdown on protesters, but said that he will press ahead with social, economic and political reforms.

Protesters seized the streets of Cairo overnight, battling police with stones and firebombs, burning down the ruling party headquarters, and defying a night curfew enforced by a military deployment. It is the peak of unrest posing the most dire threat to Mubarak in his three decades of authoritarian rule.

The government's attempts to suppress demonstrations appeared to be swiftly eroding support from the U.S. - suddenly forced to choose between its most important Arab ally and a democratic uprising demanding his ouster. Washington threatened to reduce a $1.5 billion program of foreign aid if Mubarak escalated the use of force.

The protesters were emboldened by their success in bringing tens of thousands to the streets in defiance of the ban, a large police force, countless canisters of tear gas, and even a nighttime curfew enforced by the first military deployment of the crisis.

Flames rose in cities across Egypt as police cars burned and protesters set the ruling party headquarters in Cairo ablaze. Hundreds of young men tore televisions, fans and stereo equipment from other buildings of the National Democratic Party neighboring the Egyptian Museum, home of King Tutankhamun's treasures and one of the country's most popular tourist attractions.

Young men could be seen forming a human barricade in front of the museum to protect it.

Others around the city looted banks, smashed cars, tore down street signs and pelted armored riot police vehicles with paving stones torn from roadways.

"We are the ones who will bring change," said 21-year-old Ahmed Sharif. "If we do nothing, things will get worse. Change must come!" he screamed through a surgical mask he wore to ward off the tear gas.

Egypt's national airline halted flights for at least 12 hours and a Cairo Airport official said a number of international airlines had canceled flights to the capital, at least overnight.

Options appeared to be dwindling for Mubarak, a 82-year-old former air force commander who until this week maintained what looked like rock-solid control of the most populous Arab nation and the cultural heart of the region.

With looting and arson fires rocking the capital, Mubarak seemed faced with the choice between a deadly crackdown and major concessions to protesters demanding he step down this year and not hand power to his son, Gamal.

The once-unimaginable scenes of anarchy along the Nile played out on television and computer screens from Algiers to Riyadh, two weeks to the day after protesters in Tunisia drove out their autocratic president. Images of the protests in the smaller North African country emboldened Egyptians to launch four straight days of increasingly fearless demonstrations organized over mobile phone, Facebook and Twitter.

The government cut off the Internet and mobile-phone services in Cairo on Friday, called the army into the streets and imposed a nationwide night-time curfew. The extreme measures were ignored by tens of thousands of rich, poor and middle-class protesters who united in rage against a regime seen as corrupt, abusive and neglectful of the nearly half of Egypt's 80 million people who live below the poverty line of $2 a day.

"All these people want to bring down the government. That's our basic desire," said protester Wagdy Syed, 30. "They have no morals, no respect, and no good economic sense."

Until Mubarak's brief appearance on television early Saturday morning, he made no public appearance or statement and other senior figures in the regime were also notably absent.

Egypt has been one of the United States' closest allies in the region since President Anwar Sadat made peace with Israel in 1979 after talks at Camp David.

Mubarak kept that deal after Sadat's 1981 assassination and has been a close partner of every U.S. president since Jimmy Carter, helping Washington exert its will on issues that range from suppressing Islamist violence to counterbalancing the rise of Iran's anti-American Shiite theocracy.

The government's self-declared crowning legacy has been its economic achievements: rising GDP and a surging private sector led by a construction boom and vibrant, seemingly recession-proof banks.

But many say the fruits of growth in this formerly socialist economy have been funneled almost entirely to a politically connected elite, leaving average Egyptians surrounded by unattainable symbols of wealth such as luxury housing and high-priced electronics as they struggle to find jobs, pay daily bills and find affordable housing.

Friday's unrest began when tens of thousands poured into the streets after noon prayers, stoning and confronting police who fired back with rubber bullets and tear gas. Demonstrators wielding rocks, glass and sticks chased hundreds of riot police away from the main square in downtown Cairo and several of the policemen stripped off their uniforms and badges and joined the demonstrators.

An Associated Press reporter saw the protesters cheering the police who joined them and hoisting them on their shoulders.

Security officials said there were protests in at least 11 of the country's 28 provinces, and unrest roiled major cities like Alexandria, Suez, Assiut and Port Said. Demonstrators were seen dragging blooded, unconsciousness fellow protesters to waiting cars and on to hospitals, but no official number of wounded was immediately available.

According to medical sources at least five protesters have been killed and 1,030 wounded in Cairo. Thirteen were killed in Suez and six in Alexandria, putting the current death count at 24.

The uprising united the economically struggling and the prosperous, the secular and the religious. The country's most popular opposition group, the Islamist Muslim Brotherhood, did not advertise its presence and it was not immediately clear how much of a role it played in bringing people to the streets.

Many protesters chanted "God is great!" and stopped their demonstrations to pray.

Young men in one downtown square clambered onto a statue of Talat Harb, a pioneering Egyptian economist, and unfurled a large green banner that proclaimed "The Middle Class" in white Arabic lettering.

In downtown Cairo, people on balconies tossed cans of Pepsi and bottles of water to protesters on the streets below to douse their eyes, as well as onions and lemons to sniff, to cut the sting of the tear gas.

Some of the most serious violence Friday was in Suez, where protesters seized weapons stored in a police station and asked the policemen inside to leave the building before they burned it down. They also set ablaze about 20 police trucks parked nearby. Demonstrators exchanged fire with policemen trying to stop them from storming another police station and one protester was killed in the gun battle.

Protesters appeared unfazed by the absence of Nobel Peace laureate Mohamed ElBaradei, one of the country's leading pro-democracy advocates. The former head of the International Atomic Energy Agency was soaked with a water cannon as protests erupted after Friday, and then prevented by police from leaving after he returned to his home.

The White House praised ElBaradei and said the government's policy of keeping him under house arrest had to change.

Mubarak has not said yet whether he will stand for another six-year term as president in elections this year. He has never appointed a deputy and is thought to be grooming his son Gamal to succeed him despite popular opposition.