A sea mine has exploded off the Romanian holiday resort town of Costinesti.
The incident comes as Russia appears to be targeting approaches to Ukraine’s Danube ports.
Costinesti is located near Constanta on the Black Sea coastline around 209 km (130 miles) south of the country’s border with Ukraine.
The explosion is said to have happened around 9am on Monday morning.
There are no reports of injuries as a result of the explosion, which is under investigation.
Mines have previously been detected near Romania’s coastline and it has sent a minesweeper to the area.
The incident occurred just a day after the Russian Navy fired warning shots and boarded the 3,270-dwt Sukru Okan (built 1989) after the ship’s captain failed to respond to a request to halt for an inspection over the weekend.
The ship was heading to the port of Izmail on the Danube.
Russia has been targeting Ukraine’s Danube river ports of Reni and Izmail with drone attacks.
It has said it will treat any ships approaching Ukrainian ports as potential military vessels, and their flag countries as combatants on the Ukrainian side.
The heightened tension in the region comes after the collapse of the Black Sea Grain Initiative to allow Ukraine seaborne grain exports from the ports of Odesa, Chernomorsk and Yuzhny for humanitarian reasons.
To replace the initiative, Ukraine is planning to ship more of its grain by barge from Reni and Izmail along the Danube to Constanta for export by commercial shipping.
Despite the safety threat, small general cargo ships continue to trade to the ports of Izmail and Reni, although war risk underwriters have suspended cover to the region amid the growing tension.
Ukraine also attacked a Russian oil tanker and a warship at its Novorossiysk naval base near a major grain and oil port.
