The Bulgarian navy frigate Verni has set out again from the Burgas naval base for ABLE, a cargo ship hit by drones in the Black Sea. The Defence Ministry confirmed the move this morning and said an operation is being prepared, but gave no details.

The Palau-flagged ship is drifting with no crew about 55 nautical miles north-east of Cape Emine. A fire broke out on board after the attack. All 18 crew members were evacuated, and two of them were hurt.

Yesterday Verni inspected ABLE to find out where it was, what state it was in and whether there was any debris around it. The frigate then went to the Varna area, and today it headed for the ship again.

Three days after the attacks in Bulgaria's exclusive economic zone, it is still unclear who carried them out and what drones were used. It is also unclear what cargo the second ship hit, the Alfa Vatan, was carrying.

The Alfa Vatan sank. There is no information on its crew, and the search has stopped. It has not been confirmed that the ship was carrying salt. Some claim it had weapons or even soldiers on board, but there is no proof.

Syria has asked the Bulgarian authorities and the International Maritime Organization to investigate the sinking in a transparent way.