Ukrainian riot police early today poured into Kiev's Independence Square, confronting opposition leaders and protesters demonstrating against a government decision to rebuild trade ties with Russia rather than move closer to the European Union.
Black-helmeted police entered the square in the heart of the snowbound capital where the demonstrators have been camping out for the past 10 days, tearing down barricades erected by the protesters.
Clashes broke out as police tried to detain some of the protesters. On one of the main streets leading into the square, a large group of protesters in hard hats, appointed to protect the demonstrators, held back a separate unit of riot police.
In emotional scenes, priests intoned prayers from a stage on the square and urged police not to use violence. Ruslana, a Ukrainian singer, called from a loud hailer: "Do not hurt us!"
Some protesters held mobile phones in the air like candles and sang the national anthem, while church bells rang out from a cathedral about 2 km (about 1 mile) away as in times of danger centuries ago.
The police move came after President Viktor Yanukovich on Tuesday defended his decision to walk away from signing a major trade pact with the EU on November 21 and instead revive economic links with Russia, Ukraine's former Soviet master.
Despite their large numbers, police did not initially use force but simply herded back protesters against a stage that opposition leaders have used in recent weeks as a platform from which to call for the government's dismissal.
They made no attempt to take down the encampment of tents on the square.
But clashes between the protesters' security guards and police nonetheless broke out as police tried to make arrests. Interfax news agency said some people had been hurt but it could not give an exact tally.
The police action drew an immediate response from the United States, which on Tuesday sent U.S. assistant secretary of state Victoria Nuland to Kiev, as well as the European Union.
"The United States expresses its disgust with the decision of Ukrainian authorities to meet the peaceful protest in Kyiv's Maidan Square with riot police, bulldozers, and batons, rather than with respect for democratic rights and human dignity," U.S. Secretary of State John Kerry said in a statement.
"This response is neither acceptable nor does it befit a democracy," he said in a statement in which he urged the authorities to show restraint.
EU foreign policy chief Catherine Ashton, who is also in Kiev and was expecting to meet Yanukovich on Wednesday, said in a statement: "I observe with sadness that police use force to remove peaceful people from the centre of Kyiv. The authorities did not need to act under cover of night to engage with society by using police."
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.