An undated photo shows the Maltese-registered, Finnish-chartered cargo vessel Arctic Sea that mysteriously disappeared last month and was found off Cape Verde on Monday. ((Sovfracht/Reuters))

Eight men have been arrested in connection with the hijacking of a Russian-manned freighter that was forced to sail from Scandinavia to West Africa, Russia's defence minister said Tuesday.

The suspected hijackers — citizens of Estonia, Latvia and Russia — were arrested without incident by the Russian navy after it found the Arctic Sea Monday off Cape Verde, thousands of kilometres from the Algerian port where it was supposed to dock two weeks ago, Anatoly Serdyukov said in Moscow.

It is still unclear why the Arctic Sea, an 18-year-old ship with a cargo of timber worth $2.2 million, was seized. Its disappearance had perplexed experts and officials across Europe.

Serdyukov recounted for reporters what the 15-member Russian crew and owner of the Arctic Sea told officials.

The freighter left the Finnish port of Pietarsaari on July 21. On July 30, Swedish police said the ship's owner had reported it was boarded by masked men on July 24 near the Swedish island of Gotland. The invaders reportedly had tied up the crew members, beat them, claimed they were looking for drugs, and then sped off about 12 hours later in an inflatable craft.

The hijackers reportedly got aboard under the pretext that there was a problem with their inflatable craft. The hijackers, who were armed, then forced the crew to change course and turned off the Arctic Sea's navigation equipment.