Fresh riots erupted in several Egyptian cities, including Cairo as thousands of angry protesters continued to roam the streets after the 4 pm (1400 GMT) curfew started, defying an army warning that anyone violating the order would be in danger.

They thronged central Cairo, where army armoured vehicles were stationed. Protesters also stayed out in Alexandria.

'It does not feel like there is a curfew, I can see thousands marching next to me,' a witness told Reuters from Alexandria, Egypt's second largest city.

Tens of thousands of angry citizens took their deadly revolt to the streets of the capital for a fifth day demanding President Hosni Mubarak's ouster with dissident Mohamed ElBaradei vowing to press the embattled president until he goes.

The former head of the UN nuclear watchdog said 'the only way to end unrest was for Mubarak to step down and set a framework for transition of power.'

'The system of Hosni Mubarak has failed to achieve the political, economic and social demands of the Egyptian people and we want to build a new Egypt founded on freedom, democracy and social justice,' he told Al Jazeera in a phone interview.

ElBaradei, a possible candidate in Egypt's presidential election this year, flew back to Cairo from Vienna on Thursday amid unprecedented protests against Mubarak's 30-year rule.

'The main demand is that President Mubarak announces clearly that he will resign, or that he will not run again.'

Mubarak, whose government rules with emergency laws, had ordered troops and tanks into cities on Friday night in an attempt to quell demonstrations. 

According to ElBaradei, Mubarak's speech on Friday, in which he said he would form a new government, was 'disappointing' for Egyptians.

The protesters dismissed Mubarak's offer of dialogue and called on troops to come over to their side.

Meanwhile, Egypt's armed forces urged citizens to defend themselves from looters and protect the country, as nationwide protests gave way to pillaging and police were hardly visible on the streets.

They called 'on the Egyptian people to protect the nation, Egypt, and themselves' as widespread looting hit Cairo, in what amounts to an admission that troops deployed Thursday are unable to control the situation on their own.

Looters broke into the Egyptian Museum during anti-government protests late on Friday and destroyed two Pharaonic mummies, Egypt's top archaeologist told state television.

The museum in central Cairo, which has the world's biggest collection of Pharaonic antiquities, is adjacent to the headquarters of the ruling National Democratic Party that protesters had earlier set ablaze.

Flames were seen still pouring out of the party headquarters early on Saturday. 'I felt deeply sorry today when I came this morning to the Egyptian Museum and found that some had tried to raid the museum by force last night,' Zahi Hawass, chairman of the Supreme Council of Antiquities, said on Saturday.

Al Jazeera meanwhile reported that police had opened fire on 1,000 Egyptian protesters trying to storm the Interior Ministry in Cairo.

The president ordered troops and tanks into Cairo and other cities overnight and imposed a curfew in a bid to quell unrest in which dozens of people were killed. It looked increasingly as if the army held the key to the nation's future.

In an effort to appease the protesters, he dismissed his cabinet and said he would listen to their demands of reform.

The protesters, many of them young urban poor or students, are enraged over endemic poverty, corruption and unemployment as well as the lack of democracy in the most populous Arab nation. They pledged to press on with protests until Mubarak quits.

The unrest, which follows the overthrow of Tunisian strongman Zine al-Abidine Ben Ali two weeks ago in a popular uprising, has sent shock waves through the Middle East, where other autocratic rulers may face similar challenges.

Several thousand people flocked to central Cairo's Tahrir Square on Saturday, waving Egyptian flags and pumping their arms in the air in unison. 'The people demand the president be put on trial,' they chanted.

Troops backed by tanks looked on but made no attempt to break up the demonstration. Protesters encouraged them to support their cause.

The scene contrasted with Friday, when police fired teargas and rubber bullets, protesters hurled stones in running battles.

While the police are generally feared as an instrument of repression, the army is seen as a national institution.

However, the armed forces warned that the protesters would be in danger if they failed to disperse when curfew started.

Key role for army

One Middle East expert, Rosemary Hollis, of London's City University, told Reuters the army had to decide whether it stood with Mubarak or the people.

'It's one of those moments where as with the fall of communism in Eastern Europe they can come down to individual lieutenants and soldiers to decide whether they fire on the crowd or not.'

In Alexandria, police used teargas and live ammunition against demonstrators. 'We are not demanding a change of cabinet, we want them all to leave, Mubarak before anyone else,' said Saad Mohammed, a 45-year-old welder in Tahrir Square.

According to a Reuters tally, at least 74 people have been killed during the week although there was no official figure. Medical sources said at least 1,030 people were injured in Cairo.

Government buildings, including the ruling party headquarters, still blazed on Saturday morning after being set alight by demonstrators who targeted symbols of Mubarak's rule.

As well as Cairo and Alexandria, clashes have also occurred in Suez, site of the strategically important canal.

Mubarak, a key US ally, has held power since the 1981 assassination of President Anwar Sadat by Islamist soldiers and his government still rules with emergency laws.-Reuters