Ukrainian pro-Europe demonstrators vowed to stay on the streets and continue their blockade of government buildings, despite a police threat to crack down "harshly" to enforce a court order that they disperse, Reuters said.

Kiev's November 21 decision to abandon a trade and integration deal with the EU and pursue closer economic ties with Moscow brought hundreds of thousands of demonstrators into the streets over the weekend. Protesters have since blockaded the main government headquarters and occupied Kiev's city hall.

The government ratcheted up its rhetoric on Thursday, December 5 with Prime Minister Mykola Azarov branding opponents "Nazis and criminals." Kiev's police chief, Valery Mazan, threatened to "act decisively, harshly" if the protesters defy the court order to end their blockade and occupation of government buildings.

But the protesters showed no sign of retreating, with thousands remaining steadfastly camped out in the streets deep into the night.

The crisis has exposed a gulf between Ukrainians, many from the West of the country, who hope to move rapidly into the European mainstream, and those mainly from the East who look to Moscow as a guarantor of stability.

President Viktor Yanukovich had long promised to integrate with Europe while still maintaining friendly ties with Russia. His opponents, and some former supporters, considered his sudden eastward lurch a betrayal.

It has also reignited Cold War-era antagonism between Russia and Western Europe, even as foreign ministers gathered in Ukraine for a meeting of the Organization for Security and Cooperation in Europe, a body that includes both NATO members and the countries of the former Soviet Union.

European foreign ministers used their visits to Kiev to show open solidarity with the demonstrators, beginning with Germany's Guido Westerwelle who trekked to the square to meet opposition leaders on Wednesday. He was followed by others on Thursday.

Russia's Foreign Minister Sergei Lavrov, on the sidelines of the OSCE meeting, countered by accusing the Europeans of "hysteria".

Tension could be increased even further on Friday with new court proceedings against jailed opposition leader Yulia Tymoshenko. Brussels considers her a political prisoner and had campaigned in vain for her release before Kiev broke off negotiations.