Pro-Russian protesters stand at barricades at the police headquarters in Slaviansk, April 15, 2014. [Photo/Agencies]

KIEV - The Ukrainian government launched an "anti-terror" operation Tuesday against pro-Russia activists in the eastern city of Donetsk, acting President Oleksandr Turchynov said.

"The main purpose of these actions is to protect Ukrainian citizens, to stop terror, crime and the attempts to tear apart our country," Turchynov told the parliament.

He pledged the government would take a "balanced and responsible approach" to the operation to avoid grave consequences.

Turchynov again accused Russia of fomenting the unrest in Ukraine, saying the Kremlin planned "to set on fire the country's eastern and southern regions."

The pro-Moscow movement began on the Crimea peninsula late February and spread this month to Donetsk and several other eastern cities with large Russian-speaking populations.

Pro-Moscow activists have seized government buildings in the cities, demanding a referendum on autonomy and closer ties with Russia.

During a recent operation in the industrial town of Slavyansk, Ukrainian security forces exchanged gunfire with pro-Russia protesters, causing heavy casualties on both sides.