Turkish authorities are searching for 10 people aboard a cargo ship that sank after a collision with another vessel in the Marmara Sea near Istanbul early Wednesday.

"We believe, and have more or less confirmed, that the Tugberk Imamoglu has sunk," Transport Minister Abdulkadir Uraloglu told reporters in Istanbul.

Uraloglu said all 10 crew members aboard the vessel were Turkish nationals and that attempts to reach them by mobile phone had been unsuccessful.

"We can say that the sinking occurred rapidly in 11 minutes. No one has been found alive," he added.

The bulk carrier Tugberk Imamoglu and the chemical tanker Alsu collided at around 3 a.m. local time (0000 GMT) off the city's western Silivri district, the Istanbul governor's office said in a statement.

Two helicopters and 12 search and rescue vessels are scouring the area.

The Transport Ministry's maritime directorate said that life-saving equipment, including a lifeboat belonging to the Tugberk Imamoglu, had been found floating on the surface.

"Unfortunately, the crew members were not inside," it added.

What else do we know about the missing ship?

The 90-meter (295-foot) Turkish-flagged bulk carrier was en route to the Black Sea ​port ‌of Eregli from Iskenderun when the collision happened.

According to the maritime directorate, it was carrying 4,200 tons of rolled steel.

Authorities believe it sank in waters around 900 meters deep.

The 91-meter Turkish-flagged Alsu, was sailing from Kocaeli, east of Istanbul, to the Aegean port of Aliaga. It was empty at the time of the collision and did not appear to have suffered any damage, the governor's office said.

The Sea of Marmara forms part of one of the world's busiest shipping corridors, linking the Mediterranean to the Black Sea via the Bosporus and Dardanelles straits.

Edited by: Zac Crellin

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