Riot police and anti-government protesters confronted one another throughout the night on the snow-slicked streets of Ukraine's capital and a top opposition party said heavily armed security forces broke into its offices and seized computer servers.

An opposition leader, Oleh Tyanhybok, was quoted by Ukrainian media as saying several protesters were injured in one of the confrontations, in which police tore down small tent encampments blocking access to government buildings. There were no immediate official figures on injuries, but the Tuesday incident appeared to be less violent than the club-swinging police dispersals of demonstrators a week and a half ago that galvanized anger.

The protests, in their third week, started after President Viktor 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. Police violence against those demonstrations outraged many and drove hundreds of thousands of people into the streets the past two Sundays, turnouts larger even than the mass protests of the 2004 Orange Revolution that forced a rerun of a fraudulent presidential election.

The police moves on Monday and Tuesday 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.

Authorities also appeared to have tried a deceptive feint against protesters who have occupied the city administration building and turned it into a makeshift headquarters and dormitory. A court order said the building was to be vacated by midnight and about that time, the electricity was turned off, leading to fears that police were ready to storm the site.

"People didn't know what to expect, so they left," said Ivan Kerkosh, who had been inside.

But about three hours later, the electricity was restored and protesters, annoyed or bewildered, returned inside.

Storming that building would likely have been a bloody and chaotic scene that would ratchet up Western criticism. The EU's foreign policy chief is due in Kiev Tuesday to try to help defuse tensions.

The nighttime confrontations, where protesters gingerly made their way on hilly streets where the day's heavy snowfall was trodden into ice, were tense and angry, but the rally on Independence Square retained an incongruous air of merriment. Hyperenergetic pop star Ruslana led an aerobic dance routine to warm the demonstrators against the minus 5 C (23 F) freeze and servers with trays of hot tea passed through the crowd.

Around 2.a.m, many in the area reached for their cellular phones as they received a text message addressed to protesters reading in part "You are surrounded, there are no chances." The message, sent from a number which rang to an unidentified voicemail, had no visible effect.

On Monday 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. Party member Marina Soroka also said the troops surrounded and blockaded several opposition-minded Ukrainian media outlets, making their and other media websites inaccessible.

The party is headed by imprisoned former Prime Minister Yulia Tymoshenko, a longstanding foe of Yanukovych, and is the largest opposition grouping in the parliament. Critics say Tymoshenko's conviction on abuse of office charges was a case of political revenge.

In a surprise move, Yanukovych announced he would sit down with three former Ukrainian presidents on Tuesday to discuss a way out of the crisis that has paralyzed the country. They include Viktor Yushchenko, who defeated Yanukovych in the election forced by the 2004 protests.

Ukraine's political standoff has been aggravated by its rapidly deteriorating finances. The economy has been in recession for more than a year, and the government is in desperate need of foreign funding to avoid a default. As talks stalled with the International Monetary Fund, Yanukovych has sought a bailout loan from Russia.

This former Soviet republic of 46 million people is sharply divided over the prospects of drawing closer to its powerful neighbor, Russia. Yanukovych's stronghold in eastern Ukraine, the country's industrial heartland, is dominated by Russian speakers who want closer ties to Russia, in contrast to Kiev's students and residents in the west who see better EU ties as the way forward.

Opinion polls, however, show that the EU is more popular among Ukrainians than Russia.

U.S. Ambassador to Ukraine Geoffrey Pyatt cautioned the government against using force.

"Peaceful demonstrations must be allowed to continue," he wrote on Twitter. "Dialogue and non-violence key, world watching. Opportunity must not be lost."

U.S. Vice President Joe Biden spoke with Yanukovych by phone Monday and urged him to defuse tensions and begin talks with opposition leaders, the White House said.

The protests that erupted on Nov. 21 have had an anti-Russian bent because Moscow worked hard to derail the Ukraine-EU deal, issuing threats of trade consequences.


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