The hijackers of the Maltese-flagged cargo ship Arctic Sea threatened to blow it up if their ransom demands were not met, Russian news agencies reported yesterday.

"The crew members have already confirmed that the captors demanded a ransom and threatened to blow up the vessel if their orders were not obeyed," Interfax quoted a Russian Defence Ministry spokesman as saying.

"The crew members also claim that the people who seized the Arctic Sea were armed and got rid of their weapons when the ship (Russian navy ship) Ladny ordered the dry cargo carrier's crew to stop the vessel," he said.

The crew of the mystery ship arrived on the remote African archipelago of Cape Verde on board a Russian warship yesterday amid plans to fly them back to Moscow.

A delegation from Russia's Security Council boarded the warship at the port of Sal to question the 15 crew before they could be taken to a waiting Russian plane at a nearby airport, Russian ambassador Alexander Karpuchin said.

The crew, along with eight suspected hijackers from three countries, were taken aboard the Ladny off the coast of Cape Verde on Monday at the end of a high-seas chase which lasted more than three weeks.

The crew were expected to be taken to Moscow later yesterday.

Climbing gear, flares and a high-speed inflatable boat supposedly used in the hijack were found aboard the Arctic Sea, RIA news agency quoted the spokesman as saying at a briefing for Russian media.

But the limited information from Russian authorities has failed to satisfy sceptics who voiced doubts about whether the piracy actually took place or was a convenient cover story to conceal a possible secret cargo of arms or nuclear material.

The Russian-crewed ship and its $1.3 million cargo of timber "disappeared" from radar screens off the Swedish coast as it headed towards Algeria three weeks ago, prompting speculation ranging from an attack by an organised crime gang to a top-secret spy mission. The Maltese Maritime Authority said on Tuesday that it had been following the movements of the vessel all along but there was consensus among the investigating authorities of Finland, Malta and Sweden not to disclose any sensitive information so not to jeopardise the life and safety of the people on board and the integrity of the ship.

Moscow's envoy to Nato, Dmitry Rogozin, told Russian TV channels "this was a brilliant operation with disinformation used intentionally in order not to hamper the work of the military.

"Nato didn't take part in the operation but it helped locate the whereabouts of the ship," he said without elaborating.

The agencies did not say what ransom was demanded. Nobody answered the phone when Reuters called the ministry's press service to attempt to verify the reports.

There was no comment on the eight people arrested by Russia on Tuesday after its navy "found" the missing ship the previous day in the Atlantic Ocean near the Cape Verde islands. They were held on suspicion of hijacking the vessel.

Russia said they were citizens of Estonia, Latvia and Russia who on July 24 boarded the ship, forced the crew to change route and turned off its navigation equipment.

But the official version of events has been questioned by Yulia Latynina, a leading Russian opposition journalist and commentator. "The Arctic Sea was carrying something, not timber and not from Finland, that necessitated some major work on the ship," she wrote in The Moscow Times newspaper yesterday.

During two weeks of repair works in the Russian port of Kaliningrad just before the voyage, the ship's bulkhead was dismantled so something very large could be loaded, she wrote.

"To put it plainly: The Arctic Sea was carrying some sort of anti-aircraft or nuclear contraption intended for a nice, peaceful country like Syria, and they were caught with it," she said.

Even European Commission spokesman Martin Selmayr seemed to harbour some doubts about the whole saga.

"This was in our understanding a quite unique case, the full details of which will certainly one day be made the story of a Hollywood movie," he told a regular news briefing yesterday.

EU officials said police of 22 countries had been involved in the investigation and it could be two weeks before full details emerged.

One EU official said it was not clear why it had taken several days for the ship's Finnish owners to inform the police of the incident.

"They use the term 'pirates,'" the official said of the Russian statements. "We are very careful - it's not clear whether the kind of unlawful acts conducted against this ship was piracy or another kind of unlawful act. We still need much more information."

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