World leaders have sought to keep up with fast-moving events in Ukraine
Russia has recalled its ambassador to Ukraine over what it described as the deteriorating situation in the country.
Moscow has condemned the removal of President Viktor Yanukovych, who was dismissed by MPs on Saturday.
Ukraine's newly appointed interim president, Olexander Turchynov, says the country will now focus on closer integration with the EU.
Mr Yanukovych's rejection of an EU trade deal in favour of closer ties with Russia had triggered the unrest.
EU foreign policy chief Catherine Ashton is due to arrive in Kiev on Monday to discuss EU support "for a lasting solution to the political crisis and measures to stabilise the economic situation".
US Secretary of State John Kerry has said the US strongly supports the Ukrainian parliament's vote to impeach Mr Yanukovych and call elections, the central demand of months of protests.
On Sunday, he said the vote offered "the best and most promising path forward to restore peace and stability", according to a statement.
Russia's Foreign Minister Sergei Lavrov said Ukraine's opposition "had in effect seized power in Kiev, refused to disarm and continued to place its bets on violence".
He accused them of deviating from a political deal they signed with Mr Yanukovych on Friday, which aimed to end the protests after a week in which dozens of people were killed.
Russia said late on Sunday that it had recalled its ambassador to Ukraine, Mikhail Zurabov, for consultations.
The move was announced after Mr Turchynov, a close ally of former Prime Minister Yulia Tymoshenko, gave a televised address following his appointment as interim president.
Ukrainian and European Union flags flew in front of the White House during a protest in the US on Sunday
Mourners have been laying tributes in Kiev in memory of protesters killed in clashes with police
Opposition supporters remain in Kiev's Independence Square, the focus of the anti-government protests
He vowed to set up a "government of the people", and said: "We have to return to the family of European countries."
He added: "We are ready for a dialogue with Russia... on a new, fair, equal and neighbourly basis, acknowledging and taking into account Ukraine's European choice."
Mr Turchynov said MPs had until Tuesday to form a new unity government.
Moscow recently agreed to provide $15bn (£9bn; 11bn euros) to support Ukraine's struggling economy, a move seen as a reward for Mr Yanukovych's controversial decision last year not to sign a long-planned trade deal with the EU.
But there are now fears Moscow could withdraw that offer.
A US official said US Treasury Secretary Jack Lew had discussed Ukraine with Russian Finance Minister Anton Siluanov on the sidelines of the G20 meeting in Sydney on Sunday.
Mr Siluanov reportedly left open the question of whether Russia would pay the next instalment of financial help for Ukraine, worth $2bn.
British Chancellor George Osborne said early on Monday that the UK was ready to provide financial support to Ukraine through international organisations such as the International Monetary Fund (IMF).
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