The crew and suspected hijackers of the Arctic Sea - the cargo ship found by Russia's navy off West Africa on Monday - have arrived in Moscow, BBC reported.
The four suspects - an Estonian, two Latvians and two Russians - were then taken to a high-security prison, Reuters news agency reported.
They had earlier been questioned aboard a Russian ship off Africa's coast.
The Arctic Sea was said to have gone missing on 30 July as it rounded the north-western corner of France.
Russia said its navy reached the Maltese-flagged ship on Monday, 300 miles (480 km) off Cape Verde in the Atlantic Ocean.
Speculation about what happened to the ship has included suggestions of piracy, a mafia dispute, a commercial row, smuggling or trafficking.
Correspondents say that despite the details given by Russian officials, the case is still laden with mysteries.
Carrying timber reportedly worth $1.8m (£1.1m), the 4,000-tonne Arctic Sea sailed from Finland and had been scheduled to dock in the Algerian port of Bejaia on 4 August.
Russian Defence Minister Anatoly Serdyukov says the hijackers attacked on 24 July.
They threatened to blow up the ship if their demand for a ransom was not met, Russian officials said.
Once on board, the hijackers threatened the crew with guns and forced them to turn off navigational and tracking equipment and sail south, the defence minister said.
Earlier reports said assailants had left the ship after 12 hours.
Moscow deployed vessels from its Atlantic fleet to find the Arctic Sea last week.
The hijackers were armed but abandoned their weapons when stopped, Russian officials say.
But the Malta Maritime Authority said the Arctic Sea had been "continuously tracked" from the moment it was reported to have been hijacked until the Russian navy said it had taken the ship on Monday.
Maritime officials in Malta, Finland and Sweden had not wanted "to jeopardise the life and safety of the persons on board and the integrity of the ship", it said.
Last weekend, a multinational investigation was launched after police in Finland said a ransom demand had been made, while emphasising that they could not confirm its authenticity.
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