Mystery still surrounds a missing Russian-manned cargo ship, with a sighting off Africa's Cape Verde islands still to be confirmed, BBC reported.
The Arctic Sea, with 15 Russian crew members on board, was last sighted in the Bay of Biscay on 30 July.
Cape Verde officials say they think the ship is 400 nautical miles (740km) off one of the islands.
But Moscow's envoy to Cape Verde said he had not been informed of any confirmed sighting.
The 4,000-tonne Maltese-flagged vessel, which had been carrying timber, went off radar after passing through the English Channel.
There has been huge speculation over the reason for its disappearance, ranging from pirates to a mafia dispute to a commercial quarrel.
AFP news agency quoted Finnish police as saying a ransom demand had been made of the ship's Finnish owners, Solchart Management.
A source linked to the Cape Verde coastguard told AFP the Arctic Sea was outside its territorial waters.
The coastguard was informing maritime officials about the ship's movements, the source said, adding: "When the ship enters our jurisdiction, we will decide in consultation with our partners what actions to take."
Some reports have put the ship 400 nautical miles north of the Cape Verdean island of Sao Vicente.
French intelligence said it had found a ship matching the Arctic Sea's description in the area.
The Portuguese military would not confirm one of its planes had flown over the vessel.
However, the Russian ambassador to Cape Verde, Alexander Karpushin, said he had not been officially informed of the sighting and told Russia's RAI agency the sighting was "not true".
Tom Wilkerson, chief executive officer of the US Naval Institute, told the BBC the disappearance raised a number of concerns.
"What we're looking at is a ship that's over 4,000 tonnes, with no transponder working, that now all of the world's searching capability has not been able to find.
"Just because the ship doesn't appear to have anything on it of value doesn't mean that someone can't place something there that could be very valuable, and also very dangerous."