The Ukrainian navy accuses Russia of ramming and damaging one of its tugs (GP)
Ukraine's navy says Russia has opened fire and seized three of its vessels off the coast of the annexed Crimea, in a major escalation of tensions.
It said two gunboats and a tug were captured by Russian special forces after a chase. Two Ukrainian crew members were injured.
Russia is yet to comment on the claims.
It earlier accused Ukraine of illegally entering Russian waters, blocking access to the Sea of Azov with a tanker put under a bridge in the Kerch Strait.
Ukrainian President Petro Poroshenko called an urgent meeting of his "war cabinet", his spokesperson said.
Tensions have risen in the seas off the Crimean peninsula - annexed by Russia in 2014 - in recent months.
In a statement, the Ukrainian navy said the Berdyansk and the Nikopol gunboats were hit and disabled as they tried to leave the area.
It said the tug was forced to stop. Russia earlier scrambled two fighter (BBC)