MOSCOW -- A Russian naval reconnaissance ship sank Thursday after colliding with a freighter off Istanbul, but all crew members were rescued, the Defence Ministry said.

Turkey's coastal safety authority said all 78 personnel from the Russian frigate Liman were safe, as were all crew aboard the freighter, the Togo-flagged Youzarsif H. The freighter was carrying livestock.

The Defence Ministry said a hole was punched in the starboard side of the Liman during the collision, which occurred around midday Thursday about 40 kilometres northwest of the Bosphorus Strait. The cause of the collision wasn't immediately clear.

The Liman was part of the Black Sea Fleet. The Interfax news agency reported that it spent much of the winter in the Mediterranean off the coast of Syria and returned to the Black Sea to monitor NATO exercises in February.

The rescued Russian sailors were all aboard a Turkish rescue vessel and would be picked up by a nearby Russian cargo ship, the Ulus Star, the ministry said, without specifying the number of crew members. It said the cargo ship would deliver the sailors to the home base of the Black Sea Fleet, which is on Crimea, the peninsula Russia annexed from Ukraine in 2014.

Here's the latest (all times local):

5:40 p.m.

Turkey's transportation minister says that the Togo-flagged freighter involved in the collision with a Russian navy vessel has sustained very minor damage and is able to continue sailing.

Ahmet Arslan also told Turkey's A Haber news channel that the collision in the Black Sea off Istanbul occurred in heavy fog. But he added that the exact cause is being investigated.

Arslan said: "There is only a slight damage on the freighter ship... It's on the bow of the vessel but nothing to prevent it from navigating."

Turkey's private NTV television said the vessel was taking sheep from Romania to Jordan.

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4:40 p.m.

Turkey's state-run news agency says the prime minister conveyed his "sadness" over a ship collision to his Russian counterpart through his aides, correcting an earlier report which said the two leaders had spoken on the phone.

The Anadolu Agency said Prime Minister Binali Yildirim's aides contacted Dmitry Medvedev's office to relay Turkey's message on Thursday.

The Russian navy reconnaissance ship Liman sunk off Istanbul after colliding with a freighter. All of the Russian sailors are safe.

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3:40 p.m.

Turkey's state-run news agency says that the prime minister has called his Russian counterpart to express his "sadness" over a ship collision in the Black Sea.

The Russian navy reconnaissance ship Liman has sunk off Istanbul after colliding with a freighter. All of the Russian sailors are safe.

Anadolu Agency says that Prime Minister Binali Yildirim has spoken by phone with Russian counterpart Dmitry Medvedev soon after the collision.

No other details have been provided.

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3:10 p.m.

Turkey's coastal safety authority says that a Russian navy reconnaissance ship has sunk off Istanbul after colliding with a freighter. All of the Russian sailors are safe.

Authorities say that all 78 personnel on the Russian vessel Liman are accounted for after it collided with the Togo-flagged freighter Youzarsif H. in the Black Sea. The safety authority says 15 Russian sailors had been rescued after the collision.

The freighter was carrying livestock and all of its crew is safe.

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2:30 p.m.

Russia's defence ministry says a naval reconnaissance ship is in danger of sinking in the Black Sea after colliding with another vessel.

The ministry says the Liman has a hole as a result of the collision that occurred Thursday about 40 kilometres northwest of the Bosphorus Strait.

The ministry statement, carried by Russian news agencies, says none of the crew members is hurt and they are trying to save the ship.