MOSCOW (AP) — A Russian coast guard vessel rammed a Ukrainian navy tugboat near Crimea, damaging the ship's engines and hull, the Ukrainian navy said Sunday.

The incident took place Sunday as two Ukrainian navy artillery boats and a tugboat were transiting from Odessa on the Black Sea to Mariupol in the Sea of Azov, via the Kerch Strait, a narrow passage between Crimea and the Russian mainland.

"Russian coast guard vessels (...) carried out openly aggressive actions against Ukrainian navy ships" during the transit, the Ukrainian navy statement said. It said a Russian coast guard ship damaged the tugboat's engine, hull, side railing and a lifeboat.

The statement added that Russia had been informed in advance about the planned transit.

Russia's Federal Security Service (FSB) told Russian news agencies Sunday that the Ukrainian ships held their course and violated Russian territorial waters, which were temporarily closed.

"Their goal is clear," an FSB statement said, "to create a conflict situation in the region." The statement did not mention ramming a Ukrainian tugboat.

The Interfax news agency reported later that Russia has since closed the passage to civilian traffic, citing a local port authority, due to heightened security concerns.

Though a 2003 treaty designates the Kerch Strait and Sea of Azov as shared territorial waters, Russia has been asserting greater control over the passage since 2015.

According to the Ukrainian navy, "the occupiers' dispatch service refuses to ensure the right to freedom of navigation, guaranteed by international agreements."