Kiev - Ukraine issued an arrest warrant Monday for its ousted president over "mass murder" and appealed for $35bn in Western aid as Moscow denounced Kiev's new reformist team as illegitimate.
The dramatic announcements by the nation's untested Western-leaning ministers - approved by parliament over a chaotic weekend that saw president Viktor Yanukovych go into hiding - came as the EU's top diplomat arrived in Kiev to buttress a sudden tilt away from Russia.
Three months of relentless protests over Yanukovych's decision to spurn an historic pact with the European Union in favour of closer ties with Ukraine's old masters in the Kremlin culminated in days of carnage last week in Kiev that claimed almost 100 lives.
Russia reacted with outrage to the "mutiny" in a country with centuries-old roots to Moscow, and which President Vladimir Putin views as an integral part of an economic - and possibly even military - alliance to counterweight the EU and Nato blocs.
But Western powers have cautiously thrown their weight behind the overthrow of a democratically elected leader by parliamentary action whose constitutional legitimacy remains open to debate.
Ukraine's new leaders hit the ground running on Monday by holding Yanukovych and about 50 other senior state and security officials responsible for the protesters' deaths.
"A criminal case has been launched over the mass murder of peaceful civilians. Yanukovych and a number of other officials have been put on a wanted list," acting interior minister Arsen Avakov said in a statement.
Avakov said Yanukovych had tried to flee the country on Saturday out of the eastern city of Donetsk - his political power base and bastion of pro-Russian support - before escaping to Crimea with a team of guards and a cache of weapons the next day.
He said the deposed head of state and his powerful administration chief Andriy Klyuev had since "travelled by three cars into an unknown direction, having first switched off their modes of communication".
Ukraine has been reeling from both political and financial crises that have seen the nation of 46 million face the threat of splintering between its pro-Western and more Russified regions and having to declare a devastating default.
World finance chiefs from Europe, the United States and the International Monetary Fund were discussing how to help out Ukraine - which could see $15bn promised to Yanukovych by Putin put on permanent hold.
Ukraine's interim finance minister Yuriy Kolobov said the "planned volume of macroeconomic assistance for Ukraine may reach around $35bn" by the end of next year.
He called for an international donor’s conference, an appeal also made by Greece which currently holds the EU presidency to avoid "disorder and default".
Russia's vocal displeasure at the changes convulsing its neighbour has translated into fears that Moscow's massive rescue may be abandoned after only one payment of $3bn that came through in December and has been used up.
The crisis in Ukraine also helped fuel a rise in oil prices on Monday, with analysts saying an angry Russia could halt natural gas supplies as it has done in the past.
"The threat and uncertainty surrounding Ukraine has Europe slowing exports of oil and products as they fear they may need them if they have to use them to offset the loss of Russian gas," said Phil Flynn of Price Futures Group.
Russian Prime Minister Dmitry Medvedev issued one of Moscow's firmest responses to date by condemning the "armed mutiny" in Ukraine.
"The legitimacy of a whole number of organs of power that function there raises great doubts," he was quoted as saying by Russian news agencies.
"Some of our foreign, Western partners think otherwise," Medvedev said. "This is some kind of [an] aberration."
Ukraine's new interim leader Oleksandr Turchynov warned that Kiev would have no alternative but to default on $13bn in foreign obligations due this year should the West fail to fill in for any suspended aid from Moscow.
Financial assistance was set to dominate the agenda of a two-day visit by EU foreign policy chief Catherine Ashton, whose talks on Monday with Ukraine's interim leader focused on finding a lasting solution to the political crisis and stabilising the economy.
London's Capital Economics consultancy said Ukraine probably needed a bailout of around $20bn to sustain its finances over the next year.
Adding to the diplomatic effort, Washington is sending Deputy Secretary of State William Burns to Kiev Tuesday, while Britain announced that Foreign Secretary William Hague will visit Ukraine soon.
The United States has stopped short of endorsing Ukraine's interim leader. White House spokesperson Jay Carney noted that Yanukovych was "not actively leading the country at present" and called for a technocratic government to promote early elections.
Turchynov has vowed to draw up a "government of the people" and warned Russia that he expected the Kremlin to respect Ukraine's pivot to the West.
He has until Tuesday to cobble together a coalition cabinet and find a prime minister willing to take up the challenge of keeping Ukraine from falling off the economic cliff before the presidential polls.
Turchynov is a close ally of Yulia Tymoshenko - an iconic but divisive former premier who was released by parliament on Saturday from a jail sentence she was handed by Yanukovych's team - and is not himself expected to run for the presidency.
Tymoshenko's spokesperson stressed that the 53-year-old - who appeared before the crowds in a wheelchair on Saturday because of back problems - had made no decision about running for president in May.
Her website on Monday said she had accepted an invitation from German Chancellor Angela Merkel to receive medical treatment in Berlin.