The incident prompted a distress call from the crew and caused damage to the vessel. 

Turkish broadcaster NTV Haber reported the attack on the tanker Altura on Thursday. 

The vessel was struck about 14 to 15 miles from the Bosphorus Strait early on Thursday morning. 

According to the reports, the tanker had departed from the Russian port of Novorossiysk on the northeastern coast of the Black Sea. 

It was carrying 140,000 tons of oil at the time of the incident, which occurred around 12:30 a.m. local time. 

The Altura, owned by the Istanbul-based Turkish company Pergamon Denizcilik Isletmeleri A.S., sustained damage to its upper deck and engine room after being hit by both an unmanned aerial vehicle and an unmanned surface vehicle. 

The 27 crew members, all Turkish citizens, were not injured. 

The crew requested assistance following the attack. 

Turkish Transport Minister Abdulkadir Uraloglu stated that authorities believe the engine room was specifically targeted by an unmanned marine vehicle. 

"We believe the engine room was specifically targeted," Uraloglu told 24TV in a televised interview. 

"We think this was done with an unmanned marine vehicle," he said, ruling out an aerial attack. 

Emergency operations were ongoing, with no further details immediately available on the extent of the damage or the cause of the attack. 

The Altura is a Suezmax tanker flagged under Sierra Leone and has been subject to sanctions by the UK and the EU.