The Ukrainian navy accused Russia on Sunday of opening fire on some of its ships in the Black Sea, striking one vessel and wounding a crew member.

The Ukrainian navy made the statement on its Facebook page after a day of rising tensions during which Russia stopped three Ukrainian navy vessels from entering the Sea of Azov via the Kerch Strait by placing a huge cargo ship beneath a Russian-controlled bridge.

Earlier  Ukraine accused Russia of illegally seizing three of its ships in the Black Sea after opening fire on them on Sunday, a charge that if confirmed could ignite a dangerous new crisis between the two countries.

Russia did not immediately or directly respond to the allegation, but Russian news agencies cited the FSB security service as saying it had incontrovertible proof that Ukraine had orchestrated what it called “a provocation” and would publicize its evidence soon.