Ukraine Special Forces launch anti-terrorist operations against pro-Russian armed activists 1404142.

Ukrainian special forces exchanged gunfire with a pro-Russia militia in an eastern city Sunday morning, with at least one security officer killed and five others wounded. It was the first reported gun battle in eastern Ukraine, where armed pro-Russia men have seized a number of government buildings in recent days.

Turchynov said a Security Service captain was killed and two colonels wounded in a gun battle outside Slovyansk, where the police station and the Security Service office were seized a day earlier.

Russia's Foreign Ministry said that the announcement was a "criminal order", and that it was "now the West's responsibility to prevent civil war in Ukraine".

Earlier on Sunday Ukraine's security forces announced their efforts to end the grip of separatists on Slovyansk.

Pro-Russian activists carrying automatic weapons seized government buildings in the town about 150km from the Russian border on Saturday, and set up barricades on the outskirts of Slovyansk.

Ukraine accuses Russia of trying to deepen violence and chaos in Ukraine. The Kremlin, it says, wants to undermine presidential elections on May 25 which aim to set the country back on a normal path after months of turmoil.