Two cargo ships in Bulgaria's economic zone in the Black Sea were hit by drones overnight at around 3:00 am, defence minister Dimitar Stoyanov says. A Su-25 jet is being readied to search for survivors.

Prime minister Rumen Radev said the ships were hit by sea and air drones and both took damage. No one from the crew of one ship has been found so far, and they remain missing. A fast boat picked up two injured crew members from the other ship, about 13 miles from the coast.

Stoyanov said the Su-25 can fly slower over the sea, which makes it easier to search for survivors. Two helicopters from Krumovo air base are flying to the "Chaika" military unit to pick up rescue teams and will fly further out to sea if needed.

Medical teams in Varna will treat the two injured, the minister said. He added he is ready to send more forces and equipment if needed.

Because of the incident, Prime Minister Radev called a meeting with officials from the relevant institutions.

Updated (06.10, 21:22): The sunken ship flies the flag of Togo and is called the Alfa Watan, while the second ship, which was carrying wheat, is the Dioscurias, Bulgaria's BTA news agency reports. The Alfa Watan's emergency buoy sent a distress signal at 2:54am, and at 3:05am the Dioscurias crew saw drone strikes hit the area, said chief of defence admiral Emil Eftimov. The rescue operation is under way 70 miles east of the town of Byala. Turkish and Indian nationals are among those evacuated from the Dioscurias, but there is no word yet on the crew of the sunken ship, said Varna regional governor Mario Smarkov. President Iliyana Yotova has called a meeting of the Consultative Council for National Security.

Follow-up: Frigate Verni sets sail for the second time towards the ships hit by drones in the Black Sea