Two Turkish-flagged commercial ships collided off the coast of Istanbul's Silivri district early on Wednesday, with maritime authorities saying one of the vessels is believed to have sunk after contact was lost with the ship and its 10 crew members.

The Turkish-flagged commercial vessel Alsu, which was sailing from Kocaeli to Aliaga, collided at around 3 am local time (0000GMT) with the Turkish-flagged commercial vessel Tugberk Imamoglu, which was traveling from Iskenderun Port to Karadeniz Eregli, according to the Istanbul Governor's Office.

The collision occurred 18 nautical miles south of Silivri.

The governor's office said vessels from the General Directorate of Coastal Safety and the Coast Guard Marmara and Straits Command, along with a Coast Guard helicopter, were dispatched to the scene.

Initial assessments by responding teams found no visible damage to the Alsu.

The Directorate General of Maritime Affairs said in a statement that the Tugberk Imamoglu is believed to have sunk after the vessel failed to respond to any radio calls and none of its crew members answered their phones.

The directorate said search and rescue efforts remain under way as authorities continue working to determine the fate of the missing crew.