Syrian authorities questioned why search and rescue operations were called off before the fate of 10 sailors was known.

Syria has called for an “independent and transparent” investigation into the sinking of a cargo ship in the Black Sea, demanding answers over the fate of the ship’s 10 crew members, including nine Syrians and an Egyptian, who remain unaccounted for.

The Togolese-flagged Alfa Watan, went down in Bulgaria’s exclusive economic zone early on Tuesday, amid a rising number of drone strikes hitting Black Sea shipping during the Russia-Ukraine war.

It is unclear who carried out the attack.

Mazen Aloush, from the Syria’s port authority asked the International Maritime Organization (IMO) and Bulgarian authorities to find out why a search and rescue mission was called off, before the missing sailors were found.

“Their fate is still unknown” said Aloush, adding that “the reasons that led to the suspension of search and rescue operations” had to be established.

The attack on Tuesday also hit the Palau-flagged Able, setting it ablaze. Eighteen Turkish and Indian crew members were rescued from the burning vessel, while the Alfa Watan sank.

Both commercial ships were managed by Turkey-based companies, according to the Equasis merchant shipping database.

The Syrian sailors’ union said contact with the ship’s crew had been lost and no survivors had been found after search operations were halted.

Aloush condemned the targeting of a civilian commercial vessel saying it was a serious breach of maritime security and a threat to sailors.

He said Syrian General Authority for Ports and Customs was closely monitoring the incident.

He urged ⁠authorities to use all available technical means to locate and inspect the wreckage to help establish what caused the ship to sink.

He called for international and maritime bodies to strengthen measures to help commercial shipping as attacks in the Black Sea rise.