Defiant demonstrators faced off with thousands of riot police on Kiev's central square as the sun rose Wednesday after an overnight confrontation in which police removed some barricades and tents from the protesters' camp and scuffled with demonstrators.

Squadrons of police in helmets and bearing metal shields converged about 1 a.m. on Independence Square, where anti-government protesters have been gathering around the clock to demand the resignation of the government in a crisis that threatens the leadership of President Viktor Yanukovych.

Thousands of protesters, their ranks swelling through the night, put up fierce resistance for hours, shoving back at the police lines to keep them away from key sites at the camp set up in Independence Square.

Several demonstrators and police were injured and ambulances were seen on the square. But police appeared to be under orders to refrain from using excessive force, unlike the violent beatings of protesters in recent weeks. Some policemen helped injured activists up from the ground and moved them away.

At dawn, some seven hours after the police siege began, police cordons stood almost motionless while speakers from the protest stage denounced the government and tried to raise demonstrators' spirits.

The protests began in late November when Yanukovych backed away from a pact that would deepen the former Soviet republic's economic ties with the 28-nation European Union _ a pact that surveys showed was supported by nearly half the country's people. The agreement would make Ukraine more Western-oriented and represent a significant loss of face for Russia, which has either controlled or heavily influenced Ukraine for centuries.

Demonstrators, waving EU and Ukrainian flags and singing the national anthem, shouted “Shame! Shame!” and “We will stand.” Many of the protesters, wearing orange construction hats to protect themselves from police truncheons, locked arms and simultaneously jumped  up and down to stay warm in freezing December temperatures that plunged to 12 degrees Fahrenheit. 

Scuffles broke out between police and opposition lawmakers, one of whom lay down on the snow trying to block a vehicle from advancing on the camp. An Orthodox priest sang prayers, and a popular Ukrainian rock song with the lyrics “I will not give up without a fight” blared from loudspeakers over the square. Pop singer Ruslana kept up morale by singing the national anthem and cheering protesters from the stage.

One protester stripped to his waist in the frigid air, got down on his knees and shouted “Stop this ... We are one people!”

At least one tent caught fire after a metal barrel where a fire was burning to keep demonstrators warm overturned.

After some of the barricades and tents were dismantled, police and city workers began to remove debris with bulldozers. Policemen used what appeared to be chain saws to clear the barricades.

Kiev police said authorities were merely trying to clear the streets leading to Independence Square, but not to remove the main encampment, the Ukrainian Interfax news agency reported. Police said that several of the most active demonstrators were detained.

Meanwhile, scores of protesters remained barricaded inside the Kiev city hall building, which they had been occupying for weeks. They hosed down the steps leading to the entrance with water so police would slip on the ice if they attempted to storm the building.

U.S. Secretary of State John Kerry issued a strong statement, expressing the United States' “disgust with the decision of Ukrainian authorities to meet the peaceful protest ... with riot police, bulldozers, and batons, rather than with respect for democratic rights and human dignity.”

“This response is neither acceptable nor does it befit a democracy,” said Kerry, urging authorities to show “utmost restraint” and protect human life. “As church bells ring tonight amidst the smoke in the streets of Kyiv, the United States stands with the people of Ukraine.  They deserve better.”

Opposition leader Vitali Klitschko, who is a reigning world heavyweight boxing champion, urged Ukrainians to rush to the center of the capital to defend democracy.

“We will say no to a police state, no to a dictatorship,” he told protesters in the square.

Hundreds of people heeded his call, heading to Independence Square as Kiev residents organized on social networks to arrange carpools.

Another top opposition leader, Arseniy  Yatsenyuk, told protesters that Yanukovych “has spat in the face of America, EU countries and 46 millions of Ukrainians and we will not forgive that.”

The confrontation at the protest camp unfolded as EU foreign policy chief Catherine Ashton and U.S. Assistant Secretary of State Victoria Nuland were in the city to try to talk to the government and the opposition and work out a solution to defuse the crisis.

“The authorities didn't need to act under the coverage of night to engage with the society by using police,” Ashton said in a statement after the police action started. “Dialogue with political forces and society and use of arguments is always better than the argument of force.”

The protests are the biggest since Ukraine's pro-democracy Orange Revolution. Those protests, also centered on Independence Square, known as the Maidan, succeeded in forcing the annulment of Yanukovych's fraud-tainted presidential victory in 2004, and ushered his pro-Western opponents into power. Yanukovych returned to the presidency in the 2010 vote, drawing on support from heavily industrialized eastern Ukraine where there are many Russian speakers.

Aiming to defuse the latest crisis, Yanukovych had called earlier Tuesday for the release of the demonstrators previously arrested in the protests and vowed that Ukraine is still interested in integrating with Europe.

His efforts, however, stopped far short of opposition demands that his government resign, and the two sides appeared no closer to a resolution that would chart out a secure future for their economically troubled nation.

Soon after Yanukovych spoke in a televised broadcast, Yatsenyuk told demonstrators at the square that the protest leaders were still insisting on their key demands: that Yanukovych dismiss the government, appoint a new one committed to signing an association agreement with the EU, release all the arrested protesters, and punish police who beat peaceful demonstrators.

Riot police have twice previously dispersed demonstrators with clubs and tear gas, beating some severely enough to send them to intensive care.

Tim Ash, an emerging markets analyst with Standard Bank in London, said that Yanukovych's decision to use force against demonstrators on Wednesday would only escalate the crisis.

“The result of today's actions will be an even more confrontational situation on the ground,” Ash said. “The opposition will dig in even more, demanding real changes in the administration.”

The crisis was deepened by Ukraine's troubled finances. The economy is teetering on the brink of default and Yanukovych has been scrambling to get funding either from the International Monetary Fund or From Russia. With the West condemning his actions, he is likely to renew efforts to get Russian aid, which may prompt even more protests at home, Ash said.

Moscow has worked aggressively to derail the deal with the EU and lure Kiev into its own economic group by offering price discounts and loans as well as imposing painful trade restrictions. (AP)