Opposition leaders in Ukraine emerged from crisis talks with President Viktor Yanukovich saying he had failed to give concrete answers to their demands.
After a day of clashes on the streets of the capital Kiev, the three leaders who met the president told crowds of demonstrators to prepare for a new police offensive against them.
At least three protesters have been killed in the first fatalities since protests began in November, after Mr Yanukovich ditched a trade deal with the European Union in favour of financial aid from Russia.
Ukraine's general prosecutor said two men killed in Kiev died from bullet wounds, and a third man died after plunging from the top of Dynamo football stadium while fighting with police.
The medical service for the protest movement said on Wednesday five activists had been killed.
Hundreds of people have been injured.
Opposition leader Vitaly Klitschko, a former boxer, told the thousands of protesters gathered on Kiev's Independence Square that during three hours of talks the president had given no clear response to their demands that the government be dismissed and sweeping anti-protest laws ditched.
He said police were preparing to clear protesters from the square and urged people to do all they can to stop them.
The protesters have battled police in bloody clashes near the government headquarters since Sunday night.
The demonstrations had turned more violent after the introduction of new laws criminalising protest which allow the government to jail people for five years for blockading public buildings.
On Wednesday morning, police stormed protesters' barricades on Hrushevskyy Street. Fresh clashes broke out as police arrested protesters.
Protesters could be seen on live TV coverage throwing rocks and fireworks towards police. At least one police officer threw a firebomb towards a burned bus.
Witnesses said police had tried to dismantle the camp set up by demonstrators angered by President Viktor Yanukovich's decision to shun a trade pact with the European Union in favour of Russia.