A CARGO ship with 12 crew on board and a rescue boat sent to the scene have sunk in a thunderstorm in the Black Sea off Turkey, the transport minister says, adding that three people had perished in the disaster.

Ten people were still missing, Transport Minister Binali Yilirim told the NTV news channel, while four people were rescued from the cargo ship.

The freighter sank off the small port of Sile northeast of Istanbul as it was carrying coal from Russia to Turkey's popular Mediterranean resort of Antalya, maritime authorities and the Anatolia news agency said.

The crew included 11 Ukrainians and a Russian, Anatolia reported, one of whom died while seven are still missing, Yilirim said.

He said a rescue boat later sank after waves tossed it against a sea wall, leaving two people dead and three others missing.

Anatolia said the Saint Kitts and Nevis flagged freighter, the Volga-Balt 199, had sent out a distress signal before disappearing off radar screens.

The Istanbul coast guard dispatched rescue services and a helicopter to the scene, it said.

The maritime authority had earlier reported that another freighter was in difficulty off the coast of Kilyos, a beach resort in northwest Istanbul, but that ship was now back on course.

The heavy thunderstorm has disrupted sea traffic in Istanbul, leading to the cancellation of ferries across the Bosphorus.

Originally published as 3 dead after freighter sinks off Turkey