KIEV, Ukraine — Ukraine warned that tensions were rising in the conflict-torn east, saying Russia was boosting its presence with additional supplies to rebels days after 200 separatist fighters were killed.

Donetsk faced heavy shelling Saturday night that damaged or destroyed seven buildings in the pro-Russian stronghold, the city council said on its website. Three government troops were killed in the past 24 hours and 13 were wounded, according to Ukrainian military spokesman Andriy Lysenko.

“Russia continues to send additional reinforcements, weapons, ammunition to the rebels,” Lysenko told reporters in Kiev. There’s a “high probability” Russia is preparing major provocations such as terrorist attacks or shelling that it can blame on Ukraine as a pretext to send “so-called peacekeepers” into rebel-held areas, he said.

The violence further undermines a Sept. 5 truce that had reduced civilian casualties. Ukraine said Nov. 7 that its forces killed as many as 200 insurgents in a battle for Donetsk Airport, prompting Russia to send new tanks and military vehicles across the border into rebel areas.

The Organization for Security and Cooperation in Europe said in a statement Saturday that convoys of unmarked trucks and tanks were seen in the city of Donetsk and nearby Makeevka.