Ukrainian opposition leaders have issued an ultimatum to President Viktor Yanukovych - urging him to call early elections or face more protests.
They've also called on their supporters to remain calm, after at least three demonstrators were killed in clashes in Kiev.
Barricades continue to burn on the streets of the capital.
Meanwhile - US State Department spokeswoman Marie Harf says the United States strongly condemns the violence in Ukraine and is considering sanctions:
The opposition has given the President 24 hours to discmiss the government, crap harsh anti-protest legislation and call new polls.
"You, Mr President, have the opportunity to resolve this issue," said opposition leader Vitali Klitschko, speaking to around 40,000 people in Kiev's Independence Square.
"Early elections will change the situation without bloodshed and we will do everything to achieve that."
Protestor deaths
Medics said three protestors died yesterday. Two protesters were shot, while another died from injuries sustained in a fall. One of the dead protesters was named locally as Serhiy Nihoyna.
Police have thrown stun grenades and broken through protesters' barricades, made from burnt-out buses.
Protesters have also lobbed petrol bombs at police as fighting continued on the city's snow-covered streets.
During confrontations on Wednesday, riot police beat and shot at protesters, volunteer medics and journalists.
The Interior Ministry has announced that 70 protesters have been arrested.
Prime Minister Mykola Azarov said the police did not have live ammunition and that opposition leaders should be held responsible for the deaths.
Weekend protests
Some 200,000 took to the streets at the weekend in a show of anger over the new anti-protest laws rushed through by Mr Yanukovych.
The laws allow for jail terms of up to five years for those who blockade public buildings. They also ban protesters from wearing masks or helmets.
