Demonstrators have occupied the Ukrainian capital for weeks opposing Yanukovych's decision to freeze ties with the European Union and tilt to Russia instead.
Riot police in full gear flooded Kiev, confronting protesters through the night on snow-slicked streets, while a leading opposition party said heavily armed security forces broke into its offices and seized computer servers.
Yanukovych planned to meet today with Ukraine's three former presidents in a search for a resolution to the crisis.
There were no immediate official figures on injuries, but the incident appeared to be less violent than the club-swinging police dispersals of demonstrators a week and a half ago that galvanized anger.
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The police moves were against encampments set up after Sunday's rally and no action was taken against the extensive main camp on Kiev's central Independence Square, where crowds gather around the clock.
The protests, in their third week, started after Yanukovych backed away from signing an agreement on deepening ties with the European Union, a pact that many Ukrainians desired in order to tilt West and lessen Russia's influence on the former Soviet republic.
On Sunday protesters also toppled a landmark statue of Soviet leader Vladimir Lenin in a symbolic defiance of Russian influence.
EU foreign policy chief Catherine Ashton and US Assistant Secretary of State Victoria Nuland were expected in Kiev today, set to meet with Yanukovych and the opposition.
Yanukovych was also due to meet his three predecessors, including Viktor Yushchenko, who defeated Yanukovych in the election forced by the 2004 protests, and Leonid Kuchma, who as president opted against the use of force against Orange Revolution demonstrators.
Yesterday night, Ostap Semerak of the Fatherland Party, told The Associated Press that troops broke into the party's offices, some climbing in through its windows.
The troops left after confiscating some computer equipment, he said. An Associated Press reporter later saw broken glass and smashed computers in the offices.