The party of Ukraine's jailed opposition leader Yulia Tymoshenko's said on Monday that riot police had stormed its headquarters in the capital Kiev, although the police issued a quick denial.
Batkivshchyna (Fatherland) party spokeswoman Marina Soroka wrote on her Facebook account that the Berkut riot police had "occupied the central headquarters" of the party and were "breaking down doors".
Batkivshchyna is one of the three major opposition parties in Ukraine now spearheading mass demonstrations demanding the immediate dismissal of the government over its rejection of a historic EU pact.
The party's statement prompted a swift denial from the official spokeswoman for the Kiev regional police.
"Neither the Kiev police and nor Berkut have conducted any operations in the Batkivshchyna party's office," said police spokeswoman Olga Bilyk.
The opposition party's claim came as Ukrainian police began to move hundreds of protesters away from the entrance of the main government building in central Kiev.
Tensions in the Ukrainian capital escalated on Monday as riot police moved toward a central square that saw several hundred thousand protesters gather a day earlier demanding snap parliamentary and presidential elections.