Ukrainian President Petro Poroshenko says his forces have destroyed part of a Russian armoured convoy that crossed into eastern Ukraine, adding: “We won’t tolerate any invasion.”
Military officials in Kiev said they tracked the vehicles, including armoured personnel carriers, from the border and then attacked with artillery.
Mr Poroshenko discussed the incursion with British Prime Minister David Cameron, who expressed “grave concerns” at the situation.
Later, Mr Poroshenko tweeted: “At night much of the armoured vehicles which entered Ukraine (have) been destroyed by the Ukrainian artillery. We won’t tolerate any invasion!”