Ukrainian police and protesters fought volently near the parliament building in Kyiv Tuesday, and reports say at least three demonstrators were killed.
A parliamentary deputy reported the deaths on Facebook, and medics who work in first-aid centers run by the opposition said they could confirm the account. However, there was no immediate official announcement of casualties.
Heavy fighting broke out as police tried to break up a march to the parliament building in the capital.
Video from the scene by U.S.-funded Radio Liberty showed protesters driving police into retreat with a hail of stones.
Police responded with smoke bombs, stun grenades and rubber bullets.
The protesters have been gathering for weeks to call for the ouster of President Viktor Yanukovych after he backed off a trade deal with the European Union in November in favor of closer ties with Russia.
On Monday, Russia said it will release an additional $2 billion to Ukraine to support its moribund economy, a move seen as strengthening President Yanukovych's bid to remain in power.
In Moscow, the Russian Foreign Ministry reported "the atmosphere has worsened sharply in central Kyiv." In a statement, Russian authorities blamed the violence on Western governments, accusing them of encouraging "radical forces" among the protesters.
Officials say the eurobond purchase by Moscow is in addition to the $3 billion it bought late last year. The money is part of a $15 billion loan promised by Russia.
Weeks of protests in Kyiv and other major Ukrainian cities have spawned widespread media coverage abroad and calls for more democracy in the former Soviet republic. German Chancellor Angela Merkel - a leading figure in the 28-member EU trade bloc - met Monday with two Ukrainian opposition leaders; boxer-turned-politician Vitaly Klitschko and Arseni Yatsenyuk.
Klitschko, writing ahead of the meeting in the German daily Bild, said the opposition was seeking EU support for sanctions against the Yanukovych government and EU help in curbing the powers of the Ukrainian president.
A Merkel spokesman was later quoted by Deutsche Welle as saying the chancellor voiced "sympathy for the legitimate concerns of the Ukrainian people." But he said Ms. Merkel did not agree with calls for sanctions at this time.
EU and U.S. officials have repeatedly said they are working with the International Monetary Fund on details of an aid package that analysts have described as rivaling or exceeding the Russian bailout deal. But so far no concrete offers have been made public.