Egypt's army has vowed it will not use force against the tens of thousands of people protesting for the removal of the regime of President Hosni Mubarak.
It said it respected the "legitimate rights of the people".
The statement comes ahead of a massive march planned for Cairo on Tuesday and amid a call for a general strike.
Meanwhile, new Vice President Omar Suleiman said Mr Mubarak had asked him to open dialogue with all political parties on constitutional reform.
Earlier, Mr Mubarak announced a cabinet reshuffle to try to head off the protests, replacing the widely despised Interior Minister Habib al-Adly.
Defying the curfewIn its statement, carried on Egyptian media, the military said: "To the great people of Egypt, your armed forces, acknowledging the legitimate rights of the people... have not and will not use force against the Egyptian people."
BBC Middle East editor Jeremy Bowen says the announcement is absolutely critical because it takes away a huge measure of uncertainty from the mind of any potential demonstrator.
And the BBC's Lyse Doucet, in the Egyptian capital, says people will see similarities to what happened in Tunisia, when the army's refusal to fire on protesters led to the ousting of President Zine al-Abidine Ben Ali after 23 years in power.
She says the language will appeal to the thousands of people in Cairo's central Tahrir (Liberation) Square, where there has been a very friendly atmosphere between protesters and soldiers. They are trying to defuse any tension before the mass demonstrations planned on Tuesday.
The opposition has called for a million people to take to the streets of Cairo.
A similar mass march has been called for Alexandria.
Train services in Egypt have been halted between the curfew hours of 1500 and 0800 (1300 and 0600 GMT) and EgyptAir said it was cancelling all domestic and international flights between these hours, a move correspondents say may be intended to restrict attendance at demonstrations.
However, thousands of protesters are still camped out in Tahrir Square, defying the curfew.
Leaflets were being distributed to the crowds calling on the army to take the people's side and resist orders to move against them.
The AFP news agency reports that internet service provider, the Noor Group, went down on Monday - removing the country's last remaining connection.