Il Nuovo Postiglione - 10 missing as Turkish cargo ship sinks after collision off Istanbul

The incident occurred before dawn when the ALSU, an empty oil tanker, collided with the Tugberk Imamoglu, a cargo ship carrying rolled steel which sank shortly afterwards, the transport ministry's maritime directorate said on X.

"Due to the Tugberk Imamoglu not responding to any calls and the crew not answering their mobiles... it is believed the cargo ship has sunk," it said.

The collision occurred 18 nautical miles off Silivri district on the western edge of Istanbul province, with Transport Minister Abdulkadir Uraloglu telling journalists the damaged vessel had sunk "very quickly".

"We received the emergency call at 3:26 am. If we accept the captain's reported (collision) time of 3:15, we can say the sinking occurred very rapidly, within just 11 minutes," he said.

"We spotted life buoys and a lifeboat but it was empty. Unfortunately, no survivors have been found so far," he said, indicating that search and rescue operations were ongoing.

He said there were 10 people on board: the captain and nine other crew members, all of them Turkish nationals.

The cargo ship went down in waters that were approximately 900 metres (more than half a mile) deep, with 14 vessels and a helicopter involved in search and rescue efforts, the maritime directorate said.

"Life-saving equipment, including a lifeboat belonging to the Tugberk Imamoglu which had 10 crew members on board, has been found at sea. Unfortunately, the crew members were not inside," it said.

The ALSU, which was not damaged in the collision, was also helping with the search and rescue efforts, it said.

- Human error? -

What caused the collision was not immediately clear but experts said it was likely human error.

"The Sea of Marmara is a heavily trafficked and closely monitored area, it has all the characteristics of a maritime highway," maritime engineer Sabri Gokhan told the private NTV broadcaster.

"Ships don't sink easily there. It was likely a mistake by the crew," he said.

According to the VesselFinder tracking website, the Tugberk Imamoglu is a Turkish-flagged cargo ship built in 1990 which is 90 metres (300 feet) long.

At the time of the collision, it was carrying 4,200 tons of rolled sheet metal and rebar, the authorities said.

The maritime directorate initially said the ALSU was carrying 3,000 tonnes of motor oil, but later said the tanker was empty in a detail confirmed by the governorate.

The incident took place three days after a deadly ferry accident off Northern Cyprus in which eight Turkish nationals died, with rescuers still hunting for another 20 people listed as missing.

The last fatal shipwreck in the area occurred in September 2018 when a ferry that left Bandirma on the southern shores of the Sea of Marmara -- which lies between the Black Sea and the Aegean Sea -- sank, leaving one person dead and four missing.

D.Ricci--INP