Ukraine has claimed responsibility for destroying a Russian landing ship that had docked in the besieged port city of Berdyansk.
Social media footage shows the moment an explosion rocked the Orsk battleship.
Berdyansk, which is west of the besieged port of Mariupol, was seized four days after Russia invaded Ukraine.
Russia says it has used the port as a base to ferry in equipment for its troops.
Last week, Russian media triumphantly filmed the ship unloading armoured vehicles.
Exact details of what caused the explosion remain unclear.
But Deputy Defence Minister Hanna Malyar claimed that Ukraine had hit a “huge target”, capable of carrying 400 troops, 20 tanks and 45 armoured vehicles.
Ukrainian Armed Forces tweeted footage of the explosion: “The morning starts with good news! The large landing ship “Orsk” of the Black Sea Fleet of the occupiers was destroyed in the captured Russian port of Berdyansk. Glory to Ukraine!”
They added: “The Russian occupiers are burning well!”
Last week protests were violently suppressed by Russian troops as orthodox priests in trailing vestments paraded Ukraine’s blue and yellow flag in defiance of their Russian captors in Berdyansk.
Video of the Black Sea Fleet’s Orsk Project 1171 large landing ship offloading BTR-82A vehicles in Berdyansk. https://t.co/G2RaJM1DaL pic.twitter.com/S21wCfcIbO
— Rob Lee (@RALee85) March 21, 2022
Since the invasion of Ukraine a month ago Russian forces have seized most of the Ukrainian coast along the Sea of Azov except for Mariupol, which has refused to surrender.
“It is hard to overestimate the possibilities of using this port,” the website of the Russian armed forces news outlet Zvezda (Star) said on Monday.
“Now the southern flank of the special operation can receive everything necessary at any time, including equipment and ammunition.”