A Russian naval spy ship on Thursday sank in the Black Sea off Turkey's coast after hitting a Togo-flagged vessel packed with livestock but all of its 78 crew were rescued by Turkish coastguards.

The Russian military said the Liman - a former research ship re-fitted as an intelligence vessel - had a hole ripped out of its hull in the early afternoon incident.

The collision took place in fog outside the northwestern entrance to the Bosphorus Strait, one of the world's biggest shipping thoroughfares that passes through Istanbul into the Sea of Marmara.

The Turkish coastguard said in a statement that the collision involved the Togo-flagged vessel Youzarsif H which was carrying a cargo of livestock.

It said that of 78 Russian personnel on board the ship, 63 were rescued by the Turkish coastguard and the other 15 by the Youzarsif H itself.