KIEV, Ukraine (AP) -- Ukraine's embattled president offered to make a top opposition leader prime minister, but protest leaders vowed demonstrations would continue and violence erupted early Sunday as a large crowd attacked a government hall with police stationed inside.
Arseniy Yatsenyuk, a former foreign minister who led efforts to bring Ukraine closer to the European Union, told a large crowd on Kiev's central square that President Viktor Yanukovych must still meet several key opposition demands and that talks will continue.
The overnight outburst underlined a growing inclination for radical actions among some in the protest movement that has gripped the capital for two months. More moderate opposition leaders like Yatsenyuk have tried appealing to stop the clashes, but have been booed or even sprayed with a fire extinguisher in the case of Vitali Klitschko, a heavyweight boxing champion turned opposition figure.
In the dark of night, demonstrators threw firebombs into the Ukrainian House building and setting off fireworks, and police responded with tear gas. Although the crowd created a corridor at the building's entrance apparently for police to leave, none were seen coming out.
The building under attack is about 250 meters (yards) down the street from Independence Square, where mostly peaceful demonstrations have been held around the clock since early December and where protesters have set up an extensive tent camp.
The assault started after an estimated 200 police were seen entering the building and speculation spread that they were preparing to disperse demonstrators.
The protests began in Kiev after Yanukovych shelved a long-awaited trade pact with the EU in favor of securing a bailout loan from Russia, and boiled over into violence a week ago over new anti-protest laws.
Yanukovych's latest offer, coming as protester anger rises and spreads from the capital to a wide swath of the country, appeared to have been both a concession and an adroit strategy to put the opposition in a bind.
Accepting the offer could have tarred Yatsenyuk among protesters as a sell-out, but rejecting it could make him appear obdurate and unwilling to seek a way out of the crisis short of getting everything the opposition wants. Yanukovych also offered Klitschko a deputy premiership.
Yatsenyuk told the crowd at the main protest site that a special session of parliament called for Tuesday could be decisive. Yanukovych has said that session could discuss a government reshuffle and changes to the new anti-protest laws.
"Tuesday is judgment day," Yatsenyuk told protesters, referring to the parliament session. "We do not believe a single word of theirs. We believe only actions and results."
At a later news conference, Yatsenyuk said, "we are not throwing out the proposal, but we are not accepting it, either. We are conducting serious consultations among three opposition forces."
He also said the opposition would demand that the government sign a free trade agreement with the EU and release political prisoners, including former Prime Minister Yulia Tymoshenko. The opposition also is demanding early presidential elections.
The offer came hours after the head of the country's police, widely despised by the opposition, claimed protesters had seized and tortured two policemen before releasing them. The opposition denied it and said Interior Minister Vitali Zakharchenko was making a bogus claim in order to justify a police sweep against protesters.
Three protesters have died in the past week's clashes, two of them from gunshot wounds and a third of unspecified injuries. The Interior Ministry said a policeman was found shot in the head overnight. No arrests have been made or suspects named.
In the meeting with opposition leaders where he made the offer to Yatsenyuk, Yanukovych also agreed to discuss ways of changing Ukraine's constitution toward a parliamentary-presidential republic, which was one of the demands of the opposition, according to a statement on the presidential website.
If that change went through, the prime minister would have more powers and would be elected by parliament, not appointed by the president. Yanukovych backers currently have a majority in the parliament and the next scheduled election for the legislature will be in 2017.
Earlier, Zakharchenko said the two police officers had been released with the help of negotiations involving foreign embassies. He said they had been hospitalized, but didn't give details of how they allegedly were abused. He earlier said the officers were seized by volunteer security guards at the protest gatherings in Kiev and held in the city hall, which protesters have occupied since December and turned into a makeshift dormitory and operations center.