Egypt's military rulers have agreed to speed up presidential elections, a key demand of protesters packing Cairo's Tahrir Square.
Field Marshal Mohamed Hussein Tantawi said on national TV they would happen by July 2012.
He said parliamentary elections due next week would go ahead and that a referendum on an immediate transfer of power would be organised if necessary.
It follows days of protests in Cairo's Tahrir Square over the pace of reform.
Tens of thousands of people continued to pack the square on Tuesday evening.
Witnesses said many appeared to reject the military's latest concessions, chanting: "We are not leaving, he (Tantawi) leaves."
At one point late on Tuesday evening, security forces sent a barrage of tear gas across parts of Tahrir Square forcing many protesters to temporarily flee.
The BBC's Lyse Doucet tweeted that the effects of the gas could be felt on the far edges of the square. The wail of ambulance sirens hadn't stopped for hours, she added.
The US, in its strongest comments yet on the renewed unrest in Egypt, condemned the use of "excess" force by police. At least 28 people have been killed and hundreds injured since Saturday.
US State Department spokeswoman Victoria Nuland called on Egyptian authorities to "exercise maximum restraint".
Next week's parliamentary elections are due to set in train a process of transition to democracy following the toppling of President Hosni Mubarak in February.
But many Egyptians fear the military intends to hold on to power, whatever the outcome of the polls.
Under the military's original timetable, presidential elections might not have happened until 2013.
The BBC's Kevin Connolly in Cairo says the army's readiness to bring forward presidential elections appears to be a major concession.
Field Marshal Tantawi, head of the Supreme Council of the Armed Forces, said that the military was only there to protect the people and did not seek permanent power.
"The armed forces, represented by their Supreme Council, do not aspire to govern and put the supreme interest of the country above all considerations," he said.
"They are fully prepared to immediately hand over power and to return to their original duty in protecting the homeland if that what they people want, through a popular referendum if necessary."
His announcement followed a day of crisis talks between the military and political leaders.
As the talks took place, Prime Minister Essam Sharaf spoke briefly to reporters and pleaded for calm.
"All I ask of the people is that they leave, calm down. We have responded to what they wanted. We were so close to our main goal which is the elections. This is what is important, the political shift," he said.
Tahrir Square was the focal point for protests that toppled President Mubarak.
Much of Tuesday's violence took place in the streets leading between the square and the interior ministry building, witnesses say.
One protester near the ministry was seen hanging an effigy of Field Marshal Tantawi from a traffic light.
Clashes were also reported in several other Egyptian cities including Alexandria, Suez, Port Said and Aswan.
Parliamentary elections that begin next week will be staggered over three months.
They were cast in doubt after days of protests and by the offer by the military-appointed civilian cabinet, led by Prime Minister Essam Sharaf, to resign.
The military's original timetable called for the new parliament to then choose a 100-member constituent assembly to draw up a new constitution within six months.
A referendum would then approve the document before a presidential election is held. That would mean the military still in power until late 2012 or early 2013.
Protesters, however, had demanded the presidential vote take place after the parliamentary elections.