The suspected hijackers of the Arctic Sea are being questioned in Moscow
Eight men accused of hijacking the Arctic Sea cargo ship have been charged with hijacking and piracy, Russian prosecutors have said.
The men are suspected of seizing the ship and its 15-man Russian crew after raiding it disguised as police.
The ship vanished last month days after leaving Finland with a cargo of timber. The alleged hijackers, mainly from Estonia, were taken to Russia after the ship was found nearly three weeks later off the west coast of Africa.
It was spotted up 300 miles (480km) off Cape Verde in the Atlantic Ocean on 16 August.
Observers have questioned why the alleged hijackers would risk seizing the Arctic Sea in one of Europe's busiest shipping lanes for a relatively inexpensive cargo.
There has been speculation that the ship, which was scheduled to travel to the Algerian port of Bejaia, may have been carrying an illicit cargo, possibly arms.
Their roles were set out and the plan worked out in advance
Investigative committee of Russian prosecutors
The investigative committee of Russian prosecutors said on Thursday that seven of the men had been charged with participation in the alleged hijacking, and an eighth with masterminding the operation.
"After hijacking the ship, the suspects held the crew in separate berths, in isolation, to prevent any possibility of resistance," a statement from the committee said.
"Their roles were set out and the plan worked out in advance.
"They equipped themselves ahead of time with arms to put down resistance by the ship's crew and also masks and black clothing marked with the word 'POLICE'."
The suspects have previously said they were environmentalists who boarded the ship for safety during a storm.
The 4,000-tonne Maltese-flagged Arctic Sea set sail from Finland in July with a crew of 15, and was said to have been carrying timber worth $1.8m (£1.1m).
A Russian official said this week that the ship would be searched to ensure "that there are no dark spots in this story".
On Thursday, a spokesman for the prosecutors' committee was quoted by Itar-Tass news agency as saying there was "no information that the vessel might be carrying any forbidden cargo".
Authorities have kept the 11 crew members who returned to Russia in Moscow while the investigation continues.