Ukraine has issued an arrest warrant for ousted president Viktor Yanukovych over the "mass murder" of protesters and appealed for $US35 billion ($A39 billion) in Western aid to pull the ex-Soviet country back from the brink of economic collapse.
The dramatic announcements by the country's new Western-leaning ministers - approved by parliament over a chaotic weekend that saw the pro-Russian leader flee into hiding - came as a top EU envoy flew to Kiev to buttress its sudden tilt away from Moscow.
Three months of unceasing protests over Yanukovych's decision to spurn an historic pact with the European Union in favour of closer ties with its old masters in the Kremlin culminated in days of carnage in Kiev last week that claimed almost 100 lives.
Ukraine's new interim head of the federal police said on Monday that he held Yanukovych and his team of feared security insiders directly responsible for the 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 posted on his Facebook account.
Avakov said Yanukovych had tried Saturday to flee the country out of the eastern city of Donetsk - his political power base and bastion of pro-Russian support - before travelling on 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 financial chiefs meeting in Sydney over the weekend raised the possibility of coming up with a huge rescue package that could fill in for $US15 billion promised to Yanukovych by Russian President Vladimir Putin - money that is now on potentially permanent hold.
Ukraine's interim finance minister Yuriy Kolobov said the "planned volume of macroeconomic assistance for Ukraine may reach around $US35 billion" by the end of next year.
He urged Western nations and the International Monetary Fund to convene a donor conference in the next two weeks that would focus on "allocating aid to modernise and reform Ukraine".
Russia's vocal displeasure at the changes convulsing its neighbour has translated into fears in Kiev that Moscow's massive rescue may be abandoned after only one payment of $US3 billion that came through in December and has been used up.
Ukraine's new interim leader Oleksandr Turchynov warned on Sunday that Kiev would have no choice but to default on $US13-billion in foreign obligations due this year should the West fail to fill in for Moscow's suspended aid.
Financial assistance from European powers was set to dominate the agenda of a two-day visit to Kiev by EU foreign policy chief Catherine Ashton starting Monday.
Her office said the talks with Ukraine's new leaders would focus on finding "a lasting solution to the political crisis and measures to stabilise the economic situation".
British finance minister George Osborne said the European Union stood ready to provide financial backing but failed to specify the potential amount.
