Two merchant ships were attacked by air and sea drones in the Black Sea, Bulgarian Prime Minister Rumen Radev said, with one vessel sinking and its crew missing.
The attacks occurred at around 03:00 local time (23:00 GMT), approximately 70 miles (112 km) off the coastal town of Byala in eastern Bulgaria, within the country's exclusive economic zone.
The sunken vessel, the Alfa Watan, was a Turkish-owned general cargo ship flying the flag of Togo. It was reportedly heading for Sulina, Romania. It is not clear what the ship was carrying or how many people were on board.
A Bulgarian vessel arrived at the scene but found only an overturned boat, rafts, and life jackets. A search operation has been launched for the missing crew.
The second ship struck in the attack was the Able, a grain carrier flying the flag of Palau. Its last reported position was five nautical miles (9 km) from the Alfa Watan. All 18 crew members were rescued, including two who were injured in a fire on board. Eleven were Turkish nationals and seven were Indian nationals.
Radev condemned the strikes as "a flagrant violation of maritime law." He told reporters: "Such an attack within the Bulgarian exclusive economic zone is absolutely unacceptable."
He did not attribute responsibility for the attacks but referenced the broader conflict, saying: "As I have long maintained, if this war is not halted in time, it will continue to expand its geographical reach and increase risks, including the risk of a global conflict."
Moscow has not commented on the incident.
European Commission President Ursula von der Leyen wrote on X: "The situation in the Black Sea is increasingly concerning. Commercial ships – and innocent crews – are being targeted, with lives already lost at sea. While exact circumstances of these incidents are still being established, the developments are very concerning. Attacks on civilian shipping are unacceptable."
The attacks come a day after Ukrainian President Volodymyr Zelensky accused Russia of striking a civilian vessel carrying corn.
A separate attack on Tuesday, near Odesa, killed one crew member and injured seven others. That ship was flying the flag of the Marshall Islands, according to reports.
On Sunday, Russia's defence ministry said it would intensify strikes across Ukraine in response to statements by Zelensky, in which he said Kyiv would increase attacks on Russian oil refineries.
Bulgaria's exclusive economic zone in the Black Sea covers just over 29,000 sq km (11,197 sq miles), representing approximately 6% of the total area of the Black Sea.
Russia launched a full-scale invasion of Ukraine in February 2022.
