The attack took place 300 miles (480 kilometers) off the coast of Somalia as the 16,000-ton cargo ship headed from Colombo, Sri Lanka, to the Kenyan city of Mombasa, the ministry said. The Cyprus-flagged ship, operated by a Russian company based in Vladivostok, had an all-Russian crew of 17 aboard.
The attack came a day after Russia's navy said Russian and British ships had repelled a pirate attack on a Danish freighter in the Gulf of Aden, sending up helicopters. The British military said the crew of a dhow suspected of attacking the Danish ship surrendered after a gunbattle that left two suspected pirates dead.
Russia sent the missile frigate Neustrashimy, or Intrepid, to protect Russian ships and crews off Somalia's coast after a Ukrainian freighter with three Russians aboard
-- and loaded with battle tanks -- was hijacked in September. Its captain has died, and the 20 other crew are still being held aboard the MV Faina.
Russia's Transport Ministry said the Neustrashimy was about 1,200 miles (750 miles) from the site of Thursday's attack.
Pirate attacks are common off Somalia, which has had no functioning government since 1991.
A NATO flotilla of seven vessels is also patrolling the Gulf of Aden to help the U.S. 5th Fleet in anti-piracy patrols and to escort cargo vessels.
The 5th Fleet said that it has repelled about two dozen pirate attacks since Aug 22. NATO officials said alliance warships have not fended off any attacks on the merchant ships they are protecting.