A police officer uses shields as cover while he aims a shotgun in clashes with protesters. At least two protesters were shot dead in recent clashes. Efrem Lukatsky/AP

Riot police gathering on Jan. 22 in Kiev. They attempted to storm the protesters’ barricades. Anatolii Boiko/AFP/Getty Images

A protester gestures using the arms of a broken mannequin during clashes in Kiev. Sergei Grits/AP

Anti-government protesters carry tires through a barricade of burning debris Jan. 25, 2014, as the standoff in Kiev continues. Volodymyr Shuvayev/AFP/Getty Images

Men carry a casket containing the body of Mikhail Zhiznevsky, 25, an anti-government protester who was killed in clashes with police, through the streets of downtown Kiev after a service in his honor. Brendan Hoffman/Getty Images

Protesters warm themselves at a fire behind a barricade during anti-government protests in Kiev, Jan. 27, 2014. Sergey Dolzhenko/EPA

A top Ukrainian protest leader said Saturday that the opposition is ready to lead the country, but that he would not immediately accept an invitation by embattled President Viktor Yanukovich's to become prime minister.

Arseniy Yatsenyuk's statement on Saturday came several hours after Yanukovich offered the premiership in what was seen as a move to quell protests, which have grown increasingly violent in recent days.

But the concession did little to appease demonstrators. New violence erupted in Kiev overnight, as a large crowd attacked a government conference hall where police were stationed inside.

Protestors were seen throwing firebombs into the Ukrainian House building and setting off fireworks. 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 violence flared just hours after Yatsenyuk rebuffed Yanukovich's offer.

Accepting could have tarred Yatsenyuk among protesters as a sell-out, but rejecting it would make him appear unwilling to seek a way out of the crisis short of getting everything the opposition wants.

Meanwhile fellow opposition leader Vitaly Klitschko, a former international boxing champion, was offered the deputy prime minister responsible for humanitarian issues under the presidential concessions.

But he later told German newspaper Bild am Sonntag: "This was a poisoned offer by Yanukovich to divide our protest movement. We will keep on negotiating and continue to demand early elections."

Ukraine's opposition protesters have said that they want Yanukovich to resign, early elections, and the repeal of harsh anti-protest laws that set off clashes between demonstrators and police over the past week.

Yanukovich called for a special session of parliament Tuesday and said it could discuss repealing those laws.

"Tuesday is judgment day," Yatsenyuk told a large crowd of protesters on Independence Square. "We do not believe any single word. We believe only actions and results."

Before Yanukovich made his offer, anti-government protesters on Saturday seized a regional administration building, and officials said that two police officers who had allegedly been held there by demonstrators were freed. But protesters said they had never held the officers in the first place. One protest leader called the claim a provocation aimed at justifying a crackdown.

Interior Minister Vitaly Zakharchenko, one of the government figures who protesters have heavily criticized, said the two officers were released with the help of negotiations by foreign embassies. He said they had been hospitalized, but did not give details of how they were allegedly abused.

Zakharchenko earlier said the officers were seized by volunteer security guards at the protest gatherings in Kiev. But the commandant of the corps, Mykhailo Blavatsky, told The Associated Press that no police had been seized.

"The authorities are looking for a pretext to break up the Maidan and creating all kinds of provocations," he said, referring to the main square of Kiev where around-the-clock protests have been going on for nearly two months. "Capturing a policeman would only give the authorities reason to go on the attack, and we don't need that."

Zakharchenko's claim and an earlier statement that a third captured officer had been released and was in serious condition in a hospital raised fears that police were preparing to break up the protest.

"We will consider those who remain on the Maidan and in captured buildings to be extremist groups. In the event that danger arises, and radicals go into action, we will be obliged to use force," Zakharchenko said.

Demonstrations that started in late November to protest President Viktor Yanukovich's decision to shelve a long-awaited agreement to deepen ties with the European Union had been mostly peaceful until a week ago, when radical factions enraged by new laws to crack down on protests clashed violently with police.

The clashes and the spread of unrest beyond the Ukrainian capital suggest that the government could be losing control of much of the country.

According to Nina L. Khrushcheva, a graduate professor of international affairs at New York-based university The New School, Ukraine decending into anarchy isn't out of the realm of possibility.

She believes the best move for opposition leaders is to take positions offered in the government. Refusing to do so could lead to further strife and disorganization, she said.

"If they have no government, then it's a recipe for chaos," she said, adding: "They may end up being another Syria or another Egypt. And having that in the middle of Europe is a disaster for all."