Violent clashes erupted in the Ukrainian capital Kiev as more than 100,000 people protested against a government decision to delay an association deal with the EU.
Riot police and angry demonstrators fought each other in front of government buildings as one group tried to break into the Cabinet of Ministers offices.
The protest was the biggest Ukraine has seen since the 2004 Orange Revolution.
Pro-EU supporters want Ukraine’s President Viktor Yanukovich to sign the trade pact with the European Union as agreed, during a summit in Lithuania on Friday.
His decision to pullout due to pressure from Moscow has been roundly condemned by Ukraine’s top opposition figures.
Protesters have set up a tent city in the capital vowing to stay there until they get their way.
Ukraine’s U-turn after years of negotiations stunned European leaders last week. The government explained it could not afford to break ties with Russia which is trying to bring Kiev into its own customs union.