Egypt protests: Curfew in cities as army deployed
Egypt has extended its curfew to all cities as anti-government demonstrators in Cairo besiege key buildings, including the foreign ministry and the state broadcaster.
The headquarters of the governing NDP party has been set ablaze.
President Hosni Mubarak, facing the biggest challenge to his authority of his 31 years in power, has ordered the army onto the streets of Cairo.
Earlier, it was announced he would make a statement, but he is yet to appear.
BBC security correspondent Frank Gardner said: "Every minute that goes by without the president making that address to the nation makes him look weaker and will convince people he is losing his grip."
At least 18 protesters - 13 in Suez and five in Cairo - were killed in the violence on Friday, medical sources said. That brings the death toll to at least 26 since the protests began on Tuesday.
An unconfirmed report from the Reuters news agency said as many as 1,030 people may have been injured on Friday.
Across the country, tens of thousands of protesters turned out after Friday prayers and clashed with police.
The curfew is now in effect, but live television pictures from Cairo continue to show large crowds on the streets.
Correspondents in Cairo say military helicopters are circling overhead.
Some of those breaking the curfew targeted the state broadcasting building, which is guarded by the armed forces.
Also targeted was the headquarters of the ruling NDP party - a major symbol of President Mubarak's rule regime. The BBC's Wyre Davies reported from Cairo that there was no sign of the police or military as the building was enveloped in flames.
Demonstrators have been cheering for the army, while the latter is not getting into confrontations with the people, correspondents say.
Internet and phone services - both mobile and landline - have been severely disrupted, although protesters are using proxies to work around the restrictions.
Mobile operator Vodafone Egypt said in a statement that it was obliged by law to suspend services at the request of the authorities.
Reports say Egyptian opposition figure Mohamed ElBaradei has been placed under house arrest. Earlier, he was soaked by water cannon and surrounded by police as he joined protesters on the streets of Cairo.
In Sinai, BBC Arabic said its sources reported that Bedouins were besieging a police station and armed men had taken control of the road leading to Rafah, in the Palestinian territory of Gaza.
US Secretary of State Hillary Clinton has appealed to Egypt to do "everything" to restrain the security forces, urging the government to reverse its block on mobile phone and internet communications.
She also said the protesters should not use violence.
The US counts Egypt as an ally in the Middle East and has so far been cautious about taking sides. However, White House spokesman Robert Gibbs said Washington would review its aid to Egypt based on events in the coming days.
Egypt is the fourth largest recipient of American aid, after Afghanistan, Pakistan and Israel.
Meanwhile, the US is advising its citizens to avoid non-essential travel to Egypt, and several airlines - including Egyptian and BA - have cancelled or rescheduled flights.
Inspired by Tunisia
The unrest follows an uprising in Tunisia two weeks ago, in which President Zine al-Abidine Ben Ali was toppled after 23 years in power.
Egypt has many of the same social and political problems that brought about the unrest in Tunisia - rising food prices, high unemployment and anger at official corruption.
After Friday prayers, tens of thousands of people joined protests in Cairo and other cities to demand the end of Mr Mubarak's 30-year rule.
They shouted, "Down, down with Mubarak" and, "The people want the regime to fall".
At several locations, riot police responded by firing rubber bullets and tear gas, and by using water cannon. BBC Arabic reporter Assad Sawey, in Cairo, said he was arrested and beaten by plainclothes policemen.
"They took my camera away and when they arrested me, they started beating me with steel bars, the ones used here for slaughtering animals," he said.
The BBC condemned the assault, saying it was a deliberate attack by police against which the BBC would forcefully protest.
"It is vital that all journalists, whether from the BBC or elsewhere, are allowed to do their job of bringing accurate, impartial eye witness reports to audiences around the world without fear," said BBC Global News Director Peter Horrocks.
There were also reports of clashes between protesters and police in Alexandria, Mansoura and Aswan, as well as Minya and Assiut south of Cairo, and al-Arish in the Sinai peninsula.