Russia invaded Ukraine in February 2022, and mines have since then been laid in the Black Sea by the combatants. Romanian, Bulgarian and Turkish military diving teams have been defusing those that have drifted into their waters.
The sea is crucial for shipments of grain, oil and oil products and is shared by Bulgaria, Romania, Georgia and Turkey, as well as Ukraine and Russia.
Romania’s navy said its divers were still investigating whether the explosion at the pier, which claimed no victims, was caused by a mine.
Reports of a separate mine drifting near the port of Mangalia were unfounded, it said.
Romania, both a European Union and NATO member, shares a 650-km (400 mile) border with Ukraine, is host to a U.S. ballistic missile defence system and, as of last year, has a permanent alliance battlegroup stationed on its territory.