Fresh clashes between demonstrators and police erupted in central Kiev for the fourth consecutive day over a government decision to halt integration with the European Union.
About 1,000 pro-EU protesters gathered outside the government building in the capital, demanding that President Viktor Yanukovych reverses his decision to spurn a potentially historic trade deal with the EU. His move has been widely interpreted as kowtowing to Russian pressure.
Riot police fired teargas to disperse demonstrators who hurled stones, traffic cones and other objects.
The demonstration followed a huge rally on Sunday when more than 100,000 people flocked to Kiev's European Square to protest against what they see as Ukraine's drift back into the Kremlin's sphere of influence.
It was the largest demonstration since the 2004 Orange Revolution, which brought a Western-leaning government to power.
Among the protesters were the daughter of jailed Orange Revolution leader Yulia Tymoshenko and several prominent opposition figures including heavyweight boxing champion and MP Vitali Klitschko.
"Don't let him [Yanukovych] humiliate us all in this way," Eugenia Tymoshenko said, quoting a letter from her mother. "It's our roadmap to a normal life."
The former Soviet state was due to close a free trade and political association deal with the EU but the government aborted the signing at the last minute. Moscow has been urging Kiev to sign its own customs union with Kazakhstan and Belarus instead.
The halt to the EU deal came after Ukraine's parliament voted against the release of Tymoshenko, 52, who is serving a seven-year prison sentence for abuse of office. The West said the decision was politically motivated.
Tymoshenko's freedom was one of the conditions required by the EU for Ukraine to sign the association pact.