Ukraine's presidency says a deal was reached at all-night talks on resolving the country's crisis after 75 people were killed in two days of the worst violence since Soviet times.
But the opposition did not immediately confirm agreement had been reached and diplomatic sources described the talks brokered by three European Union ministers as "very difficult".
France's foreign minister voiced caution, saying opposition leaders needed time to consult.
Three hours of fierce fighting in Kiev's Independence Square left the bodies of civilians strewn on the ground close to where talks took place.
The square had earlier been recaptured by protesters demanding President Viktor Yanukovich quit.
The president's press service said that agreement had been reached at the talks and that it would be signed in the next few hours.
Diplomatic sources said the talks have been "very difficult."
Dozens of people have been killed in the latest bout of violence between police and opposition protesters, who are demanding snap elections.
Officials said the death toll from this week's fighting is at least 75, and the violence has spread beyond the capital as well - despite a truce supposedly agreed on Thursday.
Three hours of fierce fighting in Kiev's Independence Square, which was recaptured by the protesters overnight, left the bodies of more than 20 civilians strewn on the ground.
Amid international condemnation of the violence there were signs Mr Yanukovich may be prepared to give ground. The Polish prime minister says the president told a meeting of European ministers in Kiev that he is willing to hold early elections this year.
Meanwhile, in Brussels, European Union foreign ministers agreed on sanctions against Ukraine, including visa bans, asset freezes and restrictions on the export of anti-riot equipment.
The protests first erupted in November when Mr Yanukovych rejected a landmark deal with the EU in favour of closer ties with Russia, and have escalated violently this month.
The American Secretary of State, John Kerry, called for the violence to stop, saying Ukrainians deserve far better than the senseless deaths seen in the capital Kiev.
After the bloodiest day in the country's history since independence, Mr Kerry told Mr Yanukovych, to withdraw the security forces. The US Vice-president Joe Biden had a similar message,