Kiev - Radical opposition protesters on Monday battled Ukrainian police in new clashes after bloody fighting the day earlier wounded more than 200 people amid mounting fury over draconian new anti-protest laws.
The clashes, the worst in Kiev in recent times, marked a spiralling of tensions after two months of demonstrations against President Viktor Yanukovych's refusal to sign a pact for closer integration with the EU.
Amid growing fears the police could act to violently disperse the protest, Ukraine's Prosecutor General Viktor Pshonka warned protesters to halt "mass rioting", describing it as a crime against the state.
After a night of violence that continued into the early hours, thousands of Ukrainians returned to the streets on Monday despite temperatures of -10°C.
In the epicentre of the clashes outside the entrance to the iconic Dynamo Kiev football stadium in central Kiev, both sides hunkered down behind barricades in an increasingly explosive standoff.
The protesters lobbed stones dug up from the cobbled road and flung Molotov cocktails over a 20m no-man's land at police lines.
Police responded by throwing stun grenades and occasionally using rubber bullets and tear gas.
"It is necessary to immediately halt the mass rioting which bears a threat to state security. It is not just hooliganism. It is a crime against the state," Pshonka said in a statement.Tymoshenko backs radical protesters
The burned-out wrecks of half a dozen police vehicles torched and destroyed the day earlier were used by the protesters as a barricade.
According to the Kiev health authorities, more than 100 protesters were wounded in Sunday's clashes, with four people sustaining serious injuries to eyes and limbs.
The interior ministry said more than 100 members of the security forces had been wounded.
The ministry added that 20 people had been arrested for mass rioting. US-funded Ukrainian radio station Radio Svoboda said two of its journalists had been arrested on Monday morning while filming at the scene.
Opposition leaders, including former boxing champion Vitali Klitschko and Arseniy Yatsenyuk, appeared unable to have any influence on the hard core of radical protesters and stopped short of supporting their actions.
But Ukraine's jailed former prime minister and opposition leader Yulia Tymoshenko came out in support of those clashing with police, saying she would be with them if she could.
"Protect Ukraine and do not fear anything. Ukraine has no defence other than you. You are heroes," she said in a statement read by her spokesperson to AFP.'The most repressive laws'
The White House urged an end to the violence, with US National Security Council spokesperson Caitlin Hayden saying that Washington was deeply concerned and urging "all sides to immediately de-escalate the situation".
The spokesperson warned that Washington was still considering sanctions against Ukrainian officials, a step urged by the Ukrainian opposition.
EU foreign ministers meeting in Brussels on Monday deplored the violence, saying the government was at fault for adopting the repressive laws.
The new laws allow for jail terms of up to five years for those who blockade public buildings and the arrest of protesters wearing masks or helmets. Other provisions ban the dissemination of "slander" on the internet.
The laws were passed last week in a chaotic show of hands in parliament and then signed into law by Yanukovych.
The curbs on protests were "the most solid package of repressive laws that I have seen enacted by a European parliament in decades", Swedish Foreign Minister Carl Bildt said in Brussels.
It was not clear who was behind the radicalisation of the protest, which appeared to have been a well-organised move. Ukrainian media linked the action to a hitherto little-known right-wing youth group called "Right Sector".Special commission starts work without president
In an apparent attempt to find a compromise, Klitschko on Sunday travelled to the president's luxurious Mezhygirya residence outside Kiev to meet Yanukovych in person.
The president promised to create a special commission of officials set up by national security council secretary Andriy Klyuyev to solve the crisis, the presidency announced.
Given that Klyuyev was seen as a prime figure behind the violent dispersal of previous protests, the move was greeted with derision by many in the opposition.
Pro-Yanukovych lawmaker Anna German said the commission had already started its work but without the president. Klitschko's party said Yanukovych had to be involved for it to take part.
On Sunday afternoon, some 200 000 people had filled Kiev's Independence Square and surrounding streets for a new mass rally in defiance of the protest curbs.
Protesters at the rally whistled and heckled the opposition leaders for their perceived inability to mount a stronger challenge.
With Tymoshenko serving a seven-year jail term for abuse of office, the protest leadership appears riven by rivalries ahead of presidential election next year.