A Russian frigate prevented the seizure of a vessel flying the Saudi flag from being taken over by pirates off Somalia's coast Sunday, a Russian official said.

Russian Navy spokesman Igor Dygalo said the Rabikh, which was sailing about 30 miles from the Russian frigate Neustrashimy was attacked by several pirate boats, RIA Novosti reported.

The Neustrashimy was deployed in waters off the Somali coast in late October, after Somali pirates attacked about 60 ships this year.

On Saturday, a Japanese freighter carrying South Korean and Filipino crew members was hijacked by armed pirates off Somalia in the Gulf of Aden, officials said.

The 20,000-ton cargo ship Chemstar Venus was seized, South Korean Foreign Ministry officials told the Yonhap news agency. Eighteen of the ship's 23-member crew were Filipinos and five were South Korean

It was the second hijacking of a South Korean ship since September, when a freighter was also seized by pirates off Somalia. The crew of that ship was freed unharmed after more than a month of captivity.

In September, a Ukrainian ship, the Faina, which carried tanks and heavy weaponry, was seized by pirates who have demanded a multimillion-dollar ransom in exchange for the release of the crew.

NATO and the European Union recently announced plans to increase their naval presence in the Gulf of Aden.