Protesters in Ukraine have expressed scepticism that talks between an opposition leader and President Viktor Yanukovych can make progress.
Some in the capital Kiev shouted "Shame!" and whistled as Oleg Tyagnybok told crowds in Independence Square that the talks would reduce bloodshed.
Others are reported to have set fire to tyres near opposition barricades.
Another opposition leader, Vitaly Klitschko, said that the president had made no concessions in the talks.
'Afraid of more deaths'
The boxer-turned-politician said that he feared further bloodshed.
"Hours of conversation were spent about nothing," he was quoted by the Reuters news agency as saying.
Mr Klitschko spoke to protesters manning barricades and to demonstrators in Independence Square.
"There is no sense sitting at a negotiating table with someone who has already decided to deceive you.
"I earnestly wish that there will be no bloodshed and that people are not killed... I will survive, but I am afraid there will be deaths, I am afraid of this," he said.
Mr Klitschko said that the atmosphere was still tense and that the outcome of the talks was "disappointing" for the protesters.
However nationalist Svoboda (Freedom) party leader Mr Tyagnybok insisted that the authorities had - during crisis talks lasting more than four hours on Thursday evening - promised to release activists arrested during the protests.
Mr Tyagnybok said there was "a high chance of halting the bloodshed" and that there was a proposal to create a buffer zone between protesters and security forces that would leave the main protest camp on Independence Square untouched by police.
But correspondents say that when Mr Tyagnybok asked for a show of hands as to whether the talks should continue, the response of the crowd was overwhelmingly negative.
Correspondents say it is not clear now when - if ever - the talks will resume.
Two people died in clashes in Kiev on Wednesday, the first deaths in two months of protests over EU links.
The anti-government protests flared in late November over President Yanukovych's decision to pull out of a landmark treaty with the European Union.
The crisis talks lasted for more than four hours on Thursday evening.
Sources say there could be concessions on the release of activists and repealing draconian anti-protest laws passed only last week.
The opposition had earlier demanded the government step down and new elections be called.
The BBC's Daniel Stern in Kiev says it is unclear whether the ceasefire will hold as there are thousands of people at the barricades and the atmosphere is very tense.
On Wednesday evening, the opposition had given the government a 24-hour ultimatum to meet its demands.
If those were not met, Mr Klitschko said, the protesters would go on the offensive.
The BBC's Duncan Crawford, also in Kiev, says protesters are also very angry about a video showing a protester being abused by police.
The interior ministry apologised after video footage showed the protester being stripped naked and forced to stand in the snow as police took photos of him.
The man is then struck on the back of the head by a policeman.
The ministry apologised for the "unacceptable actions of the people in police uniform".
On Thursday there were signs the protests were spreading beyond Kiev.
There were demonstrations in at least six western cities, where the pro-EU opposition has significant support.
Hundreds of protesters stormed the governor's office in the city of Rivne, shouting "Down with the gang!" in reference to Mr Yanukovych's government.
Other reports spoke of attacks on the governor's offices in Zhytomyr, Vinnytsya, Khmelnytskiy and Ivano-Frankivsk.
Prime Minister Mykola Azarov on Thursday accused protesters of trying to stage a coup.
He said: "People should not think that the government lacks available resources to put an end to this. It is our constitutional right and obligation to restore order in the country."
Hundreds of protesters and scores of police officers have been injured in clashes around Independence Square this week.
Officials confirmed two bodies were found with bullet wounds close to the scene of clashes on Wednesday.
A third activist, Yuriy Verbytsky, was found dead in a forest outside Kiev, after reportedly being abducted this week. His body is said to bear signs of torture.