ULAN BATOR - Russia's top general said on Wednesday the military would search the Arctic Sea merchant ship for a possible secret cargo when it returns to Russia from a maritime odyssey that has made headlines around the world.

Russia says the Maltese-registered Arctic Sea, officially carrying timber from Finland to Algeria, was hijacked by eight men off the coast of Sweden on July 24. This month Russian warships intercepted the vessel off the coast of Cape Verde.

We do not know yet what it is carrying, we only know it is timber. But what else it is actually transporting. It has yet to be clarified, Nikolai Makarov, chief of Russia's general staff, told reporters during an official visit to Mongolia.

We want to make sure that there is nothing but timber on board this ship. The motive for the seizure is simply not very clear, said Makarov.

The saga of the Arctic Sea sparked concern across Europe after media reported the ship may have been smuggling arms or even nuclear material to the Middle East.

Radio contact with the 4,000-tonne ship was lost after it sailed through the English Channel in late July, though maritime authorities said later that the vessel was being tracked by several nations as it made its way toward Cape Verde.

Russia has released only limited information about the ship and the group of eight men -- citizens of Estonia, Latvia and Russia -- suspected of hijacking the vessel are being kept locked away in Moscow's high security Lefortovo prison.

They have denied hijacking the Arctic Sea and say they went aboard the Arctic Sea in late July after running out of fuel. Russian investigators have also questioned the crew of the ship.

PIRATE SAGA

Piracy is extremely rare in well-policed northern European waters and maritime salts have questioned why anyone would risk targeting an aging ship carrying $2 million worth of timber and then sail for Africa.

We do not rule out the possibility that they might have been carrying not only timber, Alexander Bastrykin, head of the Prosecutor-General's main investigations unit, said in an interview with the Rossiiskaya Gazeta newspaper published on Wednesday.

This is why we need to examine the vessel; so that there are no dark spots in this story, he said. This is why we asked the crew members to stay on in Moscow; we also have to clarify whether anyone of them may be involved in these events.

The ship underwent repairs in the Russian port of Kaliningrad just before the voyage and local media have reported the ship was smuggling arms or nuclear materials to buyers in the Middle East.

Four members of the crew were left aboard the ship in Cape Verde to sail it back to Russia's Black Sea port of Novorossiysk. Makarov said the vessel was likely to arrive in the first half of September.

(Writing by Dmitry Solovyov; Editing by Guy Faulconbridge and Jon Hemming)

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