Military prosecutors and the Interior Ministry's counter-terrorism unit are searching the Chelsea-3 at the port of Burgas today. They are looking for traces of the drones that hit the ship and trying to find out what explosive was used.

The badly damaged ship drifted without steering for days off Bulgaria's Black Sea coast. It was towed to Burgas at the end of last week. The search began yesterday.

Earlier on this story: Ship Chelsea 3, hit by drones, towed to Burgas port

The Sofia Military District Prosecutor's Office is overseeing it, and the counter-terrorism unit is taking part. Maj Kiril Peychinov is the prosecutor in charge. The aim is to establish the circumstances of the attack.

Experts will examine the evidence to show where the explosive came from and what type it is. Maj Peychinov told BNT that the 15 crew members are due to give evidence before a judge.

The hull has three holes. Two are in the cargo hold, one on the port side and one on the starboard side. The third is in the stern, near the steering machinery, and it has left Chelsea-3 without steering.

Capt Zhivko Petrov, head of the Maritime Administration in Burgas, told BNT that investigators are looking for a part that entered the hold during the blast and fell to the bottom. He said he is not an expert, but in his view they are most likely testing for explosives. Investigators usually look for chemical substances to find out what kind of blast it was.

It is not yet clear whether the ship will sail again. The owner will decide its fate once the specialist agencies finish their work.

"In my view, the ship should be repaired, most likely at a Bulgarian yard. Whether here in Burgas or in Varna, the owner will decide," the captain said.

Petrov is firm about towing the damaged ship over long distances: "I personally would not do long tows in this condition."