Pro-Russia demonstrators have seized another police building, this time in the eastern Ukrainian city of Horlivka on Monday, defying a government deadline for protesters to vacate occupied buildings in exchange for amnesty.
Dozens of protesters smashed windows of the police headquarters in Horlivka and scuffled with police as they took control of the facility. Video of the confrontation showed an ambulance where injured people were being treated.
A government deadline for the protesters to leave occupied buildings in several Ukrainian cities passed without action.
The pro-Russian demonstrators, sheltering behind barricades in the occupied buildings, are demanding a referendum on whether to split with Ukraine and join Russia - similar to last month's vote in Crimea.
Ukraine's acting president Oleksandr Turchynov has threatened to launch what he called a "full-scale anti-terrorist operation" against those who have taken over the buildings. The president's office said Monday that in a telephone conversation with United Nations Secretary-General Ban Ki-moon, Mr. Turchynov said Ukraine would welcome the help of the U.N. in such an operation.
Earlier in the day, Mr. Turchynov said he is not against a national referendum on what kind of country Ukraine should be. He said he is certain a majority would support a united and independent Ukraine, possibly giving broader localized rights to the east. He said such a vote could be held at the same time as the May 25 presidential election.
In Moscow, Russian Foreign Minister Sergei Lavrov said Monday he believes Russian-speaking Ukrainians in the eastern part of the country should be part of drafting a new constitution.
Mr. Turchynov has promised amnesty for those who give up their weapons and come out peacefully. But he says he will not let Russia take over eastern Ukraine the way it annexed Crimea.
U.S. Ambassador to Ukraine Geoffrey Pyatt told VOA's Russian service that his greatest fear for the region is that the conflict devolves into greater violence, which the United States does not want.
"You have people in cities across eastern Ukraine, some of them heavily armed with Russian weapons including state-of-the art sniper rifles, Russian inventory automatic machine guns with grenade launchers. These are not peaceful protesters, this is an armed force. And I think there is a real risk that their actions could precipitate greater violence and any bloodshed of course is something that the United States will oppose."
Russia came under heavy criticism during an emergency meeting of the United Nations Security Council Sunday night.
U.S. Ambassador Samantha Power accused the Russians of "writing and choreographing" the violence in Ukraine.
British Ambassador Mark Lyall Grant says satellite images show as many as 40,000 heavily armed Russian troops massed near the Ukrainian border.
Russia insists it has the right to protect Russian speakers it says are under threat in Ukraine. Russia accuses the interim Ukrainian government of being anti-Russian and anti-Semitic extremists.
Russian Ambassador Vitaly Churkin said the West has the power and the influence to push the Ukrainians toward dialogue and away from force.
Ukraine's Ambassador Yuriy Sergeyev said Russia's comments do not correspond with reality. He called on the Russians to immediately stop violating Ukrainian sovereignty.
Ukrainian special forces and pro-Russian militia exchanged gunfire in the eastern Ukrainian city of Slovyansk Sunday, with both sides reporting casualties. Pro-Russian gunmen had taken over the Slovyansk police station and government facilities in the cities of Donetsk and Kramatorsk.
Top diplomats from Russia, the United States, Ukraine and the European Union are set to hold emergency talks on the crisis April 17 in Geneva. White House officials say U.S. Vice President Joe Biden will travel to Kyiv April 22.
On Monday in Washington, the U.S. officials signed a $1 billion loan guarantee to Ukraine. U.S. Treasury Secretary Jacob Lew said the agreement demonstrates the United States' unwavering commitment to see a stable Ukraine. Lew also warned the U.S., together with its allies, is fully prepared to impose further sanctions in Russia for its actions in Ukraine. Ukrainian Finance Minister Oleksandr Shlapak said his country is wrapping up talks with the IMF on a comprehensive economic reform program.