Despite concessions, protesters show no sign of abandoning barricades in Kiev
Ukraine's parliament is due to debate amnesty for scores of protesters arrested in anti-government demonstrations. President Viktor Yanukovych has said he wants to make the amnesty conditional on protesters leaving official buildings and taking down barricades. The opposition has so far ruled this out and is demanding early elections.
On Tuesday, Prime Minister Mykola Azarov and his cabinet resigned after months of protests.
Parliament also scrapped a controversial anti-protest law in the biggest concessions yet to opposition protesters.
Demonstrations began in November when Mr Yanukovych pulled out of a planned trade deal with the EU in favour of a $15bn bailout from Russia to bolster ailing public finances in the former Soviet state.Hours before MPs in Kiev were due to discuss a possible amnesty for protesters, the White House said the issue had been raised in a telephone conversation between Vice-President Joe Biden and President Yanukovych on Tuesday. The White House said Mr Biden welcomed "progress made today" and called on Mr Yanukovych to sign the repeal of several anti-protest laws.
"He strongly encouraged President Yanukovych to continue to work with the opposition to find compromises critical to a peaceful solution," a statement said.
"These include an amnesty law and a new government that can bring political unity, win the confidence of the Ukrainian people, and take Ukraine in the direction of Europe by strengthening democratic institutions and making the reforms necessary to achieve economic prosperity."
On Tuesday, Mr Azarov said he was stepping down to create "social and political compromise".
Parliament, in an emergency debate, voted to repeal anti-protest legislation, which among other measures banned the wearing of helmets by protesters and the blockading of public buildings.
Correspondents say Mr Azarov was deeply unpopular with the opposition, who accused him of mismanaging the economy and failing to tackle corruption.
Feelings against him grew after the protests started in November, when he described demonstrators as extremists. He was also blamed for excessive use of force by the police. Meanwhile, Russia's President Vladimir Putin has criticized what he called foreign "interference" in Ukraine.
Speaking at the end of an EU-Russia summit in Brussels, Mr Putin said visits by overseas envoys were adding to the unrest.
Riot police and protesters have endured freezing temperatures in Kiev
"I think that the Ukrainian people are capable of solving this on their own," Mr Putin said.
"I can only imagine how our European partners would respond if in the heat of a crisis in a country like Greece or Cyprus, our foreign minister would appear at one of their anti-European rallies and begin addressing them."
Correspondents say his comments appear to be a thinly veiled criticism of the EU and other Western nations that have sent a string of diplomats to Ukraine in recent weeks.
The EU's High Representative for Foreign Affairs, Catherine Ashton, has flown out to Kiev on her latest visit while the bloc's Enlargement Commissioner Stefan Fuele was also back in Ukraine for his second visit in four days.
In December, the assistant US Secretary of State Victoria Nuland handed cakes to protesters while US Senator John McCain addressed 200,000 pro-EU opposition supporters in Kiev, telling them that "America stands with you".
Protests have spread in recent days across Ukraine - even to President Yanukovych's stronghold in the east - and official buildings in several cities have been occupied. On Tuesday the interior ministry reported that protesters had stabbed and wounded three policemen in the southern city of Kherson, one of whom later died.
In total, at least five people have been killed in violence linked to the protests. Despite the president accepting their resignations, the Ukrainian cabinet can remain in their posts for 60 days until a new government is formed.
Deputy Prime Minister Serhiy Arbuzov is to assume temporary leadership of the cabinet.