Russia's state-run arms company has denied that any of its warships presently heading for Syria were carrying Mil Mi-25 helicopter gunships.
Rosoboronexport said it had tried to deliver the helicopters last month in a civilian cargo vessel, and that they were still on board that ship.
A group of Russian warships from the Black Sea, Northern and Baltic fleets are currently in transit to military exercises in the Atlantic, Mediterranean and Black seas, a Russian military official said.
Russia-owned cargo vessel Alaed had to stop off the coast of Scotland June 18 with a cargo of three Mi-25 attack helicopters on board after its British insurer Standard Club withdrew its cover for the ship. It later turned back and entered the Russian port of Murmansk.
Femco, the Russian shipping company which owns the Alaed, has criticised the insurer for what it said was its "baseless action" in withdrawing insurance cover.
Danish company United Nordic Shipping, which had chartered the Alaed, unilaterally broke off its agreement with Femco, after which Standard Club withdrew the insurance cover.
Femco later changed the ship's registration - which had originally been in the Netherlands Antilles island of Curacao - and it is now Russian-flagged.
Vyacheslav Dzirkaln, deputy head of Russia's Federal Service for Military Technical Cooperation, has said that the Russian Navy would carry out its duty to defend Russian shipping in the event of a blockade of Syria.
The helicopters were in the centre of a diplomatic row in June after the US accused Russia of supplying weapons that could be used against peaceful demonstrators in Syria.
Russian denied the accusation, saying it was only returning aircraft and air defence systems which had been repaired under a previously agreed contract, and the weapons were not capable of being used against civilians.