Nine people died during clashes between anti-government protesters and police in Ukraine's capital Kiev on Tuesday, including seven civilians and two policemen, a police spokeswoman said.
Violence erupted as Ukrainian riot police advanced on the heart of 12-week-old protests against President Viktor Yanukovich and security forces set a deadline to end disturbances.
This as European Union foreign policy chief Catherine Ashton voiced deep concern about escalating violence in Ukraine and called on the country's leadership to tackle the crisis.
"I am deeply worried about the grave new escalation in Kiev and the reported victims. I condemn all use of violence, including against public or party buildings," she said in a statement issued after a day of violent clashes between police and anti-government protesters in Ukraine.
"I urge the leadership of Ukraine to address the root causes of the crisis ... Political leaders must now assume their shared responsibility to rebuild trust and create the conditions for an effective solution to the political crisis," she said.
In turn, Germany's foreign minister urged the Ukrainian government to avoid a return to violence, as riot police advanced on Kiev's Independent Square following a day of violent clashes with opponents to President Viktor Yanukovich.
"I urge the opposing groups in Ukraine to return urgently to the path of recent days and talk about a political solution," Frank-Walter Steinmeier told his Ukrainian counterpart Leonid Kozhara by telephone, Steinmeier's office said in a statement.
"A return to violence in Ukraine is certainly no way to reach a settlement and ensure a good future for the country," the German minister told Kozhara.
This comes as anti-government protesters clashed violently with police in central Kiev on Tuesday, a day after Moscow moved to cement its influence over Ukraine with $2 billion in cash to shore up the former Soviet state's heavily indebted economy.
A parliamentary deputy said on Facebook that three demonstrators had been killed, and Ukrainian television said five protesters had been hurt in the clashes. Neither report could immediately be confirmed.
Ukraine's defense ministry ordered demonstrators to stop occupying one of its buildings.
The $2 billion injection, a resumption of a $15 billion aid package, was seen as signal that Russia believed President Viktor Yanukovich had a plan to bring street demonstrations under control and had scrapped any idea of bringing opposition leaders into government.
But as protesters and police battled on the streets, Moscow blamed the escalation as a "direct result of connivance by Western politicians and European structures that have shut their eyes ... to the aggressive actions of radical forces".
Russia had seemingly won a struggle for influence over Ukraine with the West with its fiscal package that helped persuade Yanukovich to snub a trade deal with the European Union in November. But protesters who have claimed the center of the capital, Kiev, as their own are not going quietly.
"I think Russia received some kind of assurances from the Kiev leadership that were satisfactory, because only a day before there was nothing like it," said Gleb Pavlovsky, former Kremlin adviser and political analyst in Moscow.
"I think Yanukovich showed he would stick firmly by his position in talks, he would not make excessive concessions, he would fight the radicals who are getting stronger in the opposition ... and that the (new) prime minister would not be a member of the opposition."
But rather than boosting Yanukovich, Moscow's move may have helped trigger a more violent turn in the protests, especially from those demonstrators who have a strong anti-Kremlin agenda.
Several thousand protesters torched vehicles and hurled stones in the worst violence to rock the capital Kiev in more than three weeks.
Police replied by firing rubber bullets and stun and smoke grenades from trucks and from the tops of buildings, forcing the protesters back by about 100 meters.
"The authorities do not want to compromise on any issue ... We understand that yet another odious candidate will be put forward (for prime minister), one who will be unable to restore the economy or end the political crisis," said Vyacheslav Kyrylenko, an opposition deputy.
Right Sector, a militant far-right group, added to tension by calling on people holding weapons to go to Independence Square, centre of the revolt, to protect it from a possible move by security forces to break it up.
Inside parliament, where opposition leaders brought proceedings to a halt by blocking the speaker's tribune, opposition leader Vitaly Klitschko urged Yanukovich to take riot police off the streets to avert further "conflict in society".
"It will be the decision of a real man," the boxer-turned-politician told reporters inside parliament.
The protesters had marched to the parliament building to press the opposition leaders' calls for Yanukovich to relinquish what they call his "dictatorial" powers and particularly his control of the economy and the security forces.
But when they were blocked by a line of trucks about 100 meters from the building, they hurled stones at police, a Reuters witness said, and set three trucks ablaze with petrol bombs.
As the clashes extended into early afternoon, protesters ransacked a nearby office of Yanukovich's Party of the Regions.
Yanukovich has been battling the opposition-led street protests since he walked away from a trade pact with the European Union in November and opted instead for forging closer economic ties with Russia, Ukraine's Soviet-era master.
The protests have since broadened into a revolt against perceived sleaze and corruption in the Yanukovich leadership.
REUTERS