The United States traded barbs with Russia on Saturday 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, 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 E.U 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".
Ukraine's SBU security service meanwhile announced a criminal investigation into what it said was an opposition attempt to seize power.
Yatsenyuk's party, headed by jailed former prime minister Yulia Tymoshenko, said "an announcement by the SBU is an element of a use-of-force scenario, planning the possible introduction of a state of emergency".
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". Klitschko, who long lived in Germany, was cheered by hundreds of supporters on the streets of Munich, outside the police parameter around the closely guarded conference.
Russian Foreign Minister Lavrov in turn accused the West of stoking the violence in Kiev, where top officials and political leaders had backed the protestors during visits.
Lavrov told the conference "why are many prominent EU politicians actually encouraging such actions although back home they are quick to severely punish any violations of the law?", asking "What does incitement of increasingly violent street protests have to do with promoting democracy?".
Lavrov said "why don't we hear condemnation of those who seize and hold government buildings, attack the police, torture police, use racist and anti-Semitic and Nazi slogans?".
Lavrov's attack was especially barbed since EU foreign affairs head Catherine Ashton is due to visit Kiev again next week, having previously met the government and opposition figures several times to call for peaceful dialogue.
Ukraine Foreign Minister "Leonid Kozhara" told another panel that Yanukovych had made many concessions and charged that the opposition accepted far-right and violent radicals in its ranks.
Looking toward fellow panelist Klitschko, he said "I again call the opposition today to share responsibility.
"Are you with the extremist groups who wear some logos and emblems that look like Nazi-style emblems? Are you with the extremists who attack police with Molotov cocktails or not? If you are leading the opposition, be also responsible."
In reply Klitschko said the "people are against this system, they do not see a future" with it and replied in kind that the government had cracked down harshly on the protests.
To make his point, he gave Kozhara and other panellists a book of photographs of the clashes in Kiev which the foreign minister looked at briefly before handing it back.
A senior US State Department official said that Kerry told the Ukrainian opposition leaders of Washington's continued "support for the democratic, European aspirations of the Ukrainian people".
He also sat in on a meeting with Kozhara and "expressed grave concerns about the human rights situation in Ukraine, including the case of Dymtro Bulatov", the US official said.
Activist Bulatov was abducted, tortured and then held under police guard in hospital, but German Foreign Minister Frank-Walter Steinmeier said Kozhara had told him he was free to leave the country for medical treatment if he so wished.
Kerry specifically urged Kiev "to take the next steps in its dialogue with the opposition", including releasing prisoners and forming a democratic government "that can address Ukraine's economic problems and meet the European aspirations of its people".