* Three reported dead in Kiev
* Police clash again with anti-government protesters
* U.S. revokes visas for 'several' Ukrainian officials (Recasts with PM comments, adds U.S. embassy move, third death, description)
By Pavel Polityuk and Natalia Zinets
KIEV, Jan 22 (Reuters) - Ukraine's prime minister said on Wednesday that anti-government protests had brought "terrorists" onto the streets of Kiev and pledged to punish all "criminal action", even as protesters confronted police near government headquarters.
Prime Minister Mykola Azarov, speaking to his cabinet, took a tough line on the 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.
In words that appeared to foreshadow a police crackdown, Azarov said: "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 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.
But in a move underlining U.S. criticism of his government's heavy-handed treatment of the protesters, the U.S. embassy in Kiev said it had revoked the visas of several Ukrainians linked to police violence against 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.
WEEKS OF PROTESTS
The protesters have been out on the streets since November, angered by President Viktor Yanukovich's decision to shun a trade pact with the EU and instead accept financial aid from Russia to prop up Ukraine's ailing economy.
But events took a violent turn 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.
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 the worst violence that anyone can remember in Kiev, a 200-metre stretch of the city centre close to government buildings and the parliament has been turned into a battle zone as hard-core protesters, ignoring opposition leaders' pleas only for peaceful demonstration, have bombarded police with petrol bombs and cobblestones.
Riot police have replied with rubber bullets, stun grenades and tear gas. A group of priests held the two sides apart on Tuesday but the crowds were back on Wednesday after the deaths were reported.
Yanukovich has suggested he is ready for peace talks with the opposition but these have yet to materialise and opposition leader, boxer-turned-politician Vitaly Klitschko, returned to the barricades on Tuesday after Yanukovich refused to see him.
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".
As snow fell on Wednesday, hundreds of protesters glared at police lines across a 40-metre 'no-man's land, beating on drum barrels with sticks to mimic similar action by police on their riot shields.
Riot police, known as Berkut, staged a baton-charge to push back protesters and seized canisters of harmful chemicals they said the demonstrators had been readying to use against them.
After the Berkut withdrew, protesters returned to the spot.
Earlier on Wednesday, police, using teargas, tried to dismantle a protest camp but were repelled by demonstrators hurling home-made petrol bombs, witnesses said. (Writing by Richard Balmforth; Editing by Gareth Jones)