KIEV: A new era dawned in Ukraine on Sunday as parliament appointed a pro-Western interim leader after ousted president Viktor Yanukovych fled Kiev to escape retribution for a week of deadly carnage.

The ex-Soviet state's tumultuous three-month crisis culminated in a dizzying flurry of historic changes over the weekend that saw parliament sideline the pro-Russian president and call a new poll for May 25.

Lawmakers then went a step further by approving the release from her seven-year jail sentence of former prime minister Yulia Tymoshenko, a star of the 2004 Orange Revolution who was thrown behind bars less than a year after Yanukovych came to power in 2010.

The constitutional legitimacy of parliament's actions remains an open question and Yanukovych vowed in a taped interview to fight the “bandits” who now claimed to rule Ukraine.

But Yanukovych's grasp on power was in limited evidence in Kiev on Sunday as the city's police presence vanished and protesters took control of everything from traffic management to protection of government buildings after a week of bloodshed that claimed nearly 100 lives.

The United States vowed to drum up financial help that could pull Ukraine out of a crisis sparked in November when Yanukovych spurned a historic EU deal and secured a $15-billion bailout for the struggling nation of 46 million people, from its old master Russia.

'Government of the people'

Lawmakers voted on Sunday to name close Tymoshenko ally Oleksandr Turchynov, himself only appointed parliament speaker on Saturday in place of a veteran Yanukovych supporter, as interim president tasked with forming a new government by Tuesday.

Turchynov immediately vowed to draw up a “government of the people” and urged leading lawmakers to build a new parliamentary majority that could swiftly approve stalled reforms.

“We have until Tuesday,” the 49-year-old interim leader said.

New interior minister Arsen Aviakov announced the launch of a probe into police involvement in the “execution” of protesters in a week of carnage that turned Kiev's heart into a war zone.

Yanukovych was dealt another blow when his own Regions Party issued a statement condemning him for issuing “criminal orders” that led to so many deaths.

Parliament also voted to dismiss Ukraine's Foreign Minister Leonid Kozhara after sacking the federal police chief and prosecutor general on Saturday.

And it took the symbolic step of handing over Yanukovych's marble-lined mansion outside Kiev, its vast car collection and golden toilet fixtures opened up for public viewing on Saturday, to the state.

US offers help

Western countries gave vital but cautious backing to the sweeping changes in Ukraine while Russia once again cautioned that payment of its huge bailout package was on hold.

Ukraine stands on the precipice of a default and owes nearly $13 billion in debt payments this year, money it cannot drum up on financial markets because of prohibitively expensive borrowing costs.

US Treasury Secretary Jacob Lew told a G20 meeting in Sydney that Washington “stands ready to assist Ukraine as it implements reforms to restore economic stability and seeks to return to a path of democracy and growth”.

US National Security Adviser Susan Rice warned it was in no one's interest to see crisis-hit Ukraine break apart.

German Chancellor Angela Merkel and Russian President Vladimir Putin also tried on Sunday to calm some of the Cold War-style joisting that had erupted between the West and Moscow over Ukraine's future in the past weeks.

A Merkel spokesman said the two leaders agreed on the need to preserve Ukraine territorial integrity, a reference to the deep cultural fissure that runs between the pro-European west of the country and its far more Russified east.

Russian Finance Minister Alexei Ulyukayev for his part confirmed that disbursement of the remaining $12 billion in Moscow's assistance package was on hold until the political situation in Kiev cleared up.

“The fact that the opposition groups have prevailed means that the Russia rescue deal of last December will now almost certainly be withdrawn,” said Chris Weafer of the Moscow analysts Macro Advisory.

Tymoshenko for president?

The whereabouts of Yanukovych remained a mystery amid speculation that he was hiding out in the pro-Russian east.

Turchynov and Ukraine's border service both said Yanukovych had been prevented from fleeing the country out of the eastern city of Donetsk because his charter plane did not have the required paperwork.

“When officials arrived to check the documentation they were met by armed people who offered them money to fly out urgently,” border service spokesman Serhiy Astahov told AFP.

Yanukovych claimed in his taped video message on Saturday that he would never leave Ukraine or relinquish the presidency to opponents he compared to “Nazis”.