The Russian foreign ministry sent a note of protest to Ukraine over border violation by Ukrainian soldiers, a statement said.
Moscow has demanded Kiev to stop provocations on the Russian border, which "hamper the incipient process of restoring the bilateral Russian-Ukrainian dialogue" and violate the fundamental norms of international law, Xinhua quoted the ministry as saying Friday.
"The state border was violated by armed units, as infantry vehicles crossed the border. An attempt was made to defy Russian border guards' orders," Kremlin spokesman Dmitry Peskov said.
An infantry fighting vehicle of Ukrainian armed forces crossed the Russian state border in the Rostov region of southwestern Russia earlier Friday.
Russian border guards has detained the vehicle.
