* Three reported dead in Kiev amid violent clashes
* Yanukovich holds talks with three opposition leaders
* U.S. revokes visas for 'several' Ukrainian officials
* EU expresses concern, says may also take action
Ukraine's prime minister denounced anti-government protesters as "terrorists" on Wednesday, but in what appeared to be his first real move to end weeks of unrest President Viktor Yanukovich held talks with opposition leaders.
Prime Minister Mykola Azarov's tough line, at a cabinet meeting, appeared to foreshadow a police crackdown on protesters who on Wednesday massed anew in their hundreds, inflamed by reports of at least three demonstrators dying overnight - two of them from gunshot wounds.
However Yanukovich, who has so far refused to make any concessions to the protesters, raised cautious expectations of a negotiated settlement, saying he wanted no bloodshed and agreeing to meet opposition leaders.
In a statement deploring the three deaths and urging people not to heed the calls of "political radicals", Yanukovich said: "I am against bloodshed, against the use of force, against inciting enmity and violence."
His website said talks had begun between the president, his aides and three opposition leaders - boxer-turned-politician Vitaly Klitschko, former economy minister Arseny Yatsenyuk and far-right nationalist Oleh Tyahnibok.
Yanukovich, whose decision to ditch a trade deal with the European Union and turn to Russia for financial aid sparked the mass unrest last November, has rebuffed opposition demands for the dismissal of the Azarov government and the prosecution of the interior minister for heavy-handed police tactics.
The meeting marked a small victory for the three leaders who have been seeking Yanukovich's direct participation in talks.
But it seemed unlikely they would be satisfied simply with a repetition of appeals from him to call off protesters, who have been in violent confrontation with the police since Sunday.
Even as the meeting began, black-helmeted riot police appeared to be gearing for a further attempt to push back radical protesters from a street leading to the main government building and parliament, scene of bloody clashes since Sunday.
A heavy armoured vehicle moved down the road followed by scores of police bearing shields, pushing back protesters under a curtain of smoke rising from burning tyres.
But the police operation stopped well short of Independence Square, crucible of the so-called 'Euro-Maidan' protests where hundreds of anti-government demonstrators have been camped for the past two months.
"Terrorists from the 'Maidan' (Independence Square) seized dozens of people and beat them. I am officially stating that these are criminals who must answer for their action," Azarov told a cabinet meeting on Wednesday.
Azarov accused opposition leaders of inciting "criminal action" by calling for anti-government protests, which he said destabilised the situation in Ukraine, a large former Soviet republic of 46 million people.
In a move underlining Washington's criticism of his government's heavy-handed actions, the U.S. embassy in Kiev said it had revoked the visas of several Ukrainians linked to police violence against the protesters in November and December.
It did not name the officials but said it was considering further action against those responsible for the current violence.
The European Union called on Ukraine's government and opposition to "engage in a genuine dialogue".
"I strongly condemn the violent escalation of events in Kiev overnight leading to casualties. The reported deaths of several protesters are a source of extreme worry," EU foreign policy chief Catherine Ashton said in a statement.
European Commission President Jose Manuel Barroso said the EU could also take action against Ukraine after reports of the overnight deaths.
Events took a violent turn in Kiev on Sunday after a mass rally called by the opposition to protest against sweeping new laws that ban any sort of anti-government protest.
In continued overnight violence into Wednesday, two people died from gunshot wounds, according to a statement by the general prosecutor, and a third was said to have been killed in a fall from atop the Dynamo football stadium.
Fifty people were detained overnight and 29 of them were officially charged with taking part in mass unrest, police said. A total of 167 police have been injured. There was no immediate figure for civilians injured.
Azarov said earlier on Wednesday that police deployed on the streets did not possess firearms and the interior ministry has denied that police have used guns during the crisis.
In the worst violence that anyone can remember in Kiev, a 200-metre stretch of the city centre close to government buildings has been turned into a battle zone as hard-core protesters, ignoring opposition leaders' pleas for calm, have bombarded police with petrol bombs and cobblestones.
Riot police have replied with rubber bullets, stun grenades and tear gas.
Wednesday's violence erupted ironically as Ukraine marked 'National Unification Day' - the day in 1919 which brought together that part of the country that had been under Russian rule with that which had been in the Austro-Hungarian empire.
In a Unification Day message, Yanukovich expressed the conviction that 2014 would be a year of "mutual understanding and frank discussion about our common future".