Opposition Call

People rushed to the square in response to opposition leaders' call on them to come and show solidarity with the protesters.

Vitaly Klitschko, a former heavyweight boxer who is now an opposition politician, arriving at the scene, said the police action was an indictment of Yanukovich.

"After tonight I am sure that we must call not only for the dismissal of the government but also the president," he said.

Another opposition leader, former economy minister Arseny Yatsenyuk said: "He (Yanukovich) is spitting in the faces of the United States, 28 countries of Europe, 46 million Ukrainians. We will not forgive him this. Tomorrow there will be a million people here and his regime will fall,"

About 2,000 pro-EU protesters have been huddled by braziers in their encampment on Independence Square since December 1 when a police crackdown on a small group of protesters brought tens of thousands out on to the streets.

In the past few days though, police have been gradually removing barricades around the city and pushing back protesters towards the square.

Speaking on television on Tuesday, Yanukovich showed no indication of giving in to protesters' demands for the dismissal of his government and he defended his policy shift back to Russia, saying that Ukraine had no choice but to restore close trade relations with Moscow.

But a meeting he had with Russian President Vladimir Putin last Friday has raised opposition suspicions that he has agreed to bring Ukraine into a Moscow-led customs union of ex-Soviet states. Moscow and Kiev deny this matter was discussed.

With the crisis weighing on an economy already on the brink of bankruptcy, the cost of insuring Ukrainian debt rose to the highest in four years on Tuesday, and bond prices fell sharply.

Nuland, who travelled to Kiev from Moscow, met leaders of the three main opposition parties on Tuesday and may have been expecting to see Yanukovich on Wednesday.

US Vice President Joe Biden told Yanukovich in a telephone conversation on Monday that there was a "need to immediately de-escalate the situation and begin a dialogue with opposition leaders on developing a consensus way forward for Ukraine."

Liberals and nationalists alike have taken to the streets for demonstrations, and thousands have maintained an around-the-clock protest camp in the city centre, blocking roads, besieging government buildings and occupying the capital's city hall.

The tented vigil in freezing temperatures copies a tactic from the "Orange Revolution" in 2004 which successfully overturned a fraudulent election victory by Yanukovich.