A major search-and-rescue operation is underway after two Turkish-flagged commercial vessels collided in the Sea of Marmara off Istanbul, leaving one ship and its 10-member crew unaccounted for, Turkish authorities said.

According to the Istanbul Governor's Office, the collision occurred at around 3:00 a.m. local time, approximately 18 nautical miles south of the Silivri district on Wednesday.

The Turkish-flagged ALSU, which was sailing from Kocaeli to the Aegean port of Aliağa, collided for reasons that remain under investigation with the TUĞBERK İMAMOĞLU, a bulk carrier travelling from İskenderun on Türkiye's Mediterranean coast to Karadeniz Ereğli on the Black Sea.

Large-scale search operation

The Governor's Office said no visible damage was detected aboard the ALSU during initial inspections. However, authorities have been unable to establish contact with the TUĞBERK İMAMOĞLU or its 10 crew members since the collision.

The Turkish Coast Guard, the Directorate General of Coastal Safety and Coast Guard helicopters were immediately deployed to the area, where an extensive search-and-rescue operation by sea and air remains ongoing.

Bulk carrier carrying rolled steel

According to maritime authorities, the TUĞBERK İMAMOĞLU is operated as a bulk carrier and was transporting approximately 4,199 tonnes of rolled steel when the collision occurred, while the ALSU is a chemical tanker.

Authorities have not confirmed the fate of the missing vessel or its crew, and the cause of the collision remains under investigation.