Pro-Russian protesters who broke into state security headquarters in the eastern Ukrainian city of Luhansk have seized weapons and road police have closed down entrances into the city, local police said on Monday.
"Unknown people who are in the building have broken into the building's arsenal and have seized weapons," police said in a statement.
Separately, Interior Minister Arsen Avakov said on his Facebook page that the regional administrative building in another eastern city, Kharkiv, had been cleared of "separatist" protesters.
In Donetsk Sunday, a large group of people pushed into the regional government building, barricaded the doors, and hung a Russian flag from a window. Hundreds of protesters thronged in the city square below, cheering when those inside the building tossed a Ukrainian flag out the window.
A spokesman for Ukraine's acting president, Oleksandr Turchnyov, said he canceled a trip to Lithuania Sunday and called an emergency meeting of security chiefs in Kyiv because of the protests.
Ukraine's interior minister, Arsen Avakov, posted a message on social media accusing Russia's President Vladimir Putin and former Ukrainian president Viktor Yanukovych of instigating and financing the latest protests.
Russia last month annexed the Crimean peninsula from Ukraine a controversial regional referendum declared the territory’s independent from Ukraine and paved the way to its absorption by Russian Federation.
Ukraine, the U.S. and the EU have declared the vote illegal as have most countries in the United Nations General Assembly.
On Friday, British Foreign Minister William Hague said Europe should continue its "strong and united" response to Russia's escalation of the Ukrainian crisis. He said there has only been a "token withdrawal" of troops massed near the Ukrainian border, whose presence has raised fears of a Russian invasion.
Western nations have already adopted sanctions against Russia because of its annexation of the Crimean peninsula.
Russia moved into the peninsula early last month following the ouster of Ukraine's Moscow-backed president, Viktor Yanukovych. He fled after weeks of opposition protests calling for him to step down.
Some information in this report contributed by Reuters.