Crew members of the Arctic Sea prepared to fly home to Russia from the remote African archipelago of Cape Verde, as officials explained why they kept the hijacked ship's location a secret.
This undated picture released by Maritime Bulletin Sovfracht on August 12, 2009 shows the Arctic Sea cargo ship at an unknown location.
Eleven of the 15-strong crew left a Russian warship that had brought them to the island of Sal late Wednesday, witnesses told AFP.
The group boarded a plane at Amilcar Cabral airport on the island which was heading to Moscow, an airport official said.
Four crew members had remained on board the Arctic Sea at the controls of the vessel, said Russian ambassador Alexander Karpushin, adding the ship was now 260 nautical miles (482 kilometres) off Cape Verde.
The crew, along with eight suspected hijackers from Russia, Latvia and Estonia, was taken aboard the Russian submarine hunter Ladny off the coast of Cape Verde on Monday. That ended a high-seas chase that had lasted more than three weeks.
The eight suspected hijackers, their hands cuffed behind their back and some of them shirtless, were taken under heavy escort to Sal, one of the Cape Verde islands, said journalists on the island.
Later Wednesday they were put on the same Russian Ilyushin plane that was to fly the freed crew of the Arctic Sea home to Moscow.
Russian officials earlier Wednesday questioned crew members in the hopes of shedding light on the events surrounding the Russian-owned ship's disappearance.
Fierce speculation has been raging since the 4,000-tonne ship vanished after setting sail from Finland on July 24, bound for Algeria with a cargo of timber worth 1.2 million euros (1.8 million dollars).
The ship was attacked on July 24 in Swedish territorial waters by pirates, Russian Defence Minister Anatoly Serdyukov said Tuesday, and after that had reportedly lost radio contact.
But officials revealed Wednesday that the location of the ship was known for some time but had been kept secret to protect the crew.
Malta's Maritime Authority (MMA) -- the vessel is registered in Malta -- said that the ship's whereabouts had been known "for several days" before the Russian announcement of its arrest.
Swedish, Maltese and Finnish maritime authorities had agreed not to disclose the sensitive information "in order not to jeopardise the life and safety of the persons on board and the integrity of the ship," the MMA said.
Swedish police spokeswoman Linda Widmark told AFP: "We weren't able to make this information public (on the location) in order to protect the security of the crew."
Russia also confirmed the hijackers had threatened to blow up the ship if a ransom was not paid.
"Crew members confirmed that the pirates had demanded a ransom and that if this demand was not met they would blow up the ship," said a Russian defence ministry official.
The crew also confirmed the hijackers abandoned their weapons when they were intercepted by the Ladny, the official added.
Police in Finland said the full picture was still emerging.
"The mastermind could still be on the run," Chief Superintendent Rabbe von Hertzen of Finland's National Bureau of Investigation told AFP.
"It will take months before we have an insight into what actually took place and something really of significance to tell the media," he added.
"We have at least six countries involved in some way."
Von Hertzen told reporters in Helsinki that the Arctic Sea would be released to the ship's owner after investigations had been completed and a new crew would take it to Algeria.