Sustained gunfire was heard throughout the night near the eastern Ukrainian city of Slovyansk, the stronghold of pro-Russia fighters, ahead of a second round of European-brokered talks today aimed at resolving the crisis.
The Russian Foreign Ministry issued a statement condemning what it described as a sharp escalation in the violence in eastern Ukraine, accusing the Ukrainian government of using the talks as cover for military operations against its citizens.
The fighting began when forces loyal to the Kiev government moved in to protect a television tower near the small village of Andriyivka.
Debris from the shooting was visible, including a badly damaged train and craters caused by mortar bombs or other heavy artillery.
The Russian Foreign Ministry said some people were wounded, but gave no specifics.
Government forces in recent weeks have achieved only limited results in quashing the pro-Russia groups that have declared independence for Ukraine's eastern Donetsk and Luhansk regions.
Polls have shown, however, that a majority of eastern Ukrainians support a united country, although most are too fearful of the armed separatists to say so publicly.
In one southeastern city, Mariupol, steelworkers retook government buildings from pro-Russia fighters and cleared away their barricades.
Mariupol is a major industrial city in the Donetsk region, lying on the main road between Russia and the Crimean Peninsula, which Russia annexed in March.
And in the eastern village of Velyka Novosilka, armed backers of Ukrainian unity dressed in black seized control of a police station and vowed to expel the separatists in Donetsk through force if necessary.
Other similar and apparently unaccountable groups look to be emerging elsewhere in the chaotic east.
