The United States has traded barbs with Russia over Ukraine's future as key opposition figures met US Secretary of State John Kerry amid concerns that Kiev could call in the military to end anti-government protests.
Neither side pulled any punches on Saturday, with Kerry saying that what happens in Ukraine is crucial for Europe's future while his Russian counterpart Sergei Lavrov blasted what he called wilful and two-faced Western interference.
"Nowhere is the fight for a democratic, European future more important today than in Ukraine," Kerry told political, diplomatic and military leaders at the Munich Security Conference.
"The United States and EU stand with the people of Ukraine in that fight," said Kerry, who met later Saturday with Ukrainian opposition leaders including former world boxing champion Vitali Klitschko in Munich.
Kerry said Ukrainians "are fighting for the right to associate with partners who will help them realise their aspirations - and they have decided that means their futures do not have to lie with one country alone, and certainly not coerced."
European Council President Herman Van Rompuy told another panel that the EU wanted good relations with Russia but that the Ukrainian people had to have the right to choose their own future, a future with Europe.
The West and Russia have been at loggerheads over Ukraine since President Viktor Yanukovych ditched an EU association accord in November under pressure from Moscow trying to bring its former Soviet satellite back into the fold.
His decision sparked off massive anti-government protests, which turned increasingly violent in recent weeks and forced Yanukovych's government to resign, leaving the country in limbo.
Ukrainian opposition leader Arseniy Yatsenyuk told AFP that "a military crackdown is still an option" for Kiev and called on the government "to stop any involvement of the Ukrainian military into this conflict".
For his part, Klitschko warned of "a spiral of escalation" and told journalists that in Ukraine "we must avoid the start of a civil war".
