A Togo-flagged cargo ship has been rocked by an explosion while at anchor near the mouth of the Danube in the Black Sea.

The SEAMA was in Romanian waters when its crew issued a Mayday signal, just before 7am local time (4am UTC).

The 12-person crew was evacuated by Romanian coast guards and no injuries have been reported. It is unclear if the ship is seriously damaged, though pictures shared on social media indicate the ship may be taking on water at its stern.

There has been speculation that the ship hit a sea mine. The Black Sea has been heavily mined during the Russian invasion of Ukraine, as Russian forces blockaded Ukrainian ports. Although this incident took place in Romanian waters, sea mines can sometimes slip from their moorings or move with currents.

Reports suggested the explosion occurred in the engine room.

SEAMA arrived at the Sulima anchorage, 10nm off the coast, on September 12 from Turkey. It was destined for Izmail, on the Ukrainian bank of the Danube. It was awaiting an entry slot when the incident took place.

Romania is a NATO member state and if the explosion is proven to have been caused by a Russian sea mine, it is possible the event could be considered an escalation of the conflict or an attack on the NATO alliance.

The incident comes just two days after Ukraine’s Danube Shipping Company (DSC) formally requested Romania’s Constanta port to allow ship-to-ship grain transfers, which DSC said would almost double its export capacity.

Currently, waiting times at the Black Sea port are as high as 60 days.

"If Constanta allows the development of... transhipment, the rivermen are ready to increase the volumes by another 500,000t," DSC explained.