The invaders reportedly had tied up the crew, beat them, claimed they were looking for drugs, then sped off about 12 hours later in an inflatable craft.

Serdyukov reportedly said the hijackers boarded the freighter 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, he was quoted as saying.

By the time the Swedish report of the attack had emerged, the ship had already passed through the English Channel, where it made its last known radio contact on July 28. Signals from the ship's tracking device were picked up off France's coast the next day, but that was the last known trace of it until Monday.

Serdyukov said the ship were found about 300 miles (480 kilometers) away from the island nation of Cape Verde.

The 15 crew members were safe and had been taken aboard the Russian naval vessel for questioning, Serdyukov said.

The disappearance of the 98-meter (320-foot) freighter perplexed experts and officials across Europe, with speculation about what happened ranging from its being seized by pirates to involvement in a murky commercial dispute.

Associated Press writer Mike Eckel contributed to this report.