Pro-Russia demonstrators on Monday defied a government deadline to vacate occupied buildings in exchange for amnesty, as Ukraine's interim president threatened a military crackdown.
Dozens of protesters smashed windows of the police headquarters in the eastern Ukrainian city of Horlivka and scuffled with police as they took control of the facility.
Russian President Vladimir Putin urged U.S. President Barack Obama to discourage the Ukrainian government from using force against protesters.
During a phone conversation Monday with Mr. Obama, the Russian leader denied claims of Russian agents' involvement in the protests as "speculations based on unreliable information.'' Mr. Putin said the protests vented public anger about the Ukrainian government's reluctance to recognize the interests of Russian speakers in the east.
The demonstrators are demanding a referendum on whether to split with Ukraine and join Russia - similar to last month's vote in Crimea.
Ukrainian leader Oleksandr 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.
A White House spokesman said U.S. Central Intelligence Agency director John Brennan was in the Ukrainian capital during the weekend, confirming reports in Russian media, but denying claims that the CIA encouraged Ukraine to use force on the separatists.
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."
In Luxembourg, EU foreign ministers agreed to expand the list of people subject to sanctions for their role in the Ukraine crisis. And aides to French President Francois Hollande said he and U.S. President Barack Obama shared their concerns over the crisis in a telephone call Monday.
Russia came under heavy criticism during an emergency meeting of the U.N. Security Council late Sunday. U.S. Ambassador Samantha Power accused the Russians of "writing and choreographing" the violence in Ukraine.
Top diplomats from Russia, the United States, Ukraine and the European Union are 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.
Meanwhile, 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 a stable Ukraine. Ukrainian Finance Minister Oleksandr Shlapak said his country is wrapping up talks with the IMF on a comprehensive economic reform program.
The Pentagon also confirmed a Russian SU-24 fighter aircraft flew at least 12 close-range passes Saturday near a U.S. ship in the Black Sea. A Pentagon spokesman said the USS Donald Cook was never in danger, but called the passes "provocative and unprofessional." U.S. defense officials said the action is part of a pattern of Russia's unwillingness to deescalate with Ukraine.]]