Aug. 15 (Bloomberg) -- The Finnish operator of the Arctic Sea, the Maltese-flagged freighter that disappeared in the Atlantic Ocean three weeks ago, received a ransom demand, Finnish police said.

The demand consists only of money, in an amount that’s “not huge, but let’s say it’s significant,” Markku Ranta-aho, a senior detective with Finland’s National Bureau of Investigation in Helsinki, said by phone today, declining to comment on when the demand was received. The ship’s location is still unknown, he said.

The Arctic Sea, operated by Helsinki-based Oy Solchart Management AB with a crew of 15 Russians, has been missing since July 24. The operator denied a report earlier today that the freighter communicated from the Bay of Biscay. Finland, Sweden and Malta are leading a 20-nation investigation into the disappearance, including alleged offences of aggravated extortion and hijacking, Finnish police said today.

“Public communication on the case has not been possible” because of the nature of the crime and the “significant threats to life and health,” the Finnish police said in a statement on their Web site.

Solchart Managing Director Viktor Matveyev didn’t answer calls today seeking comment on the report of the ransom demand.

The Arctic Sea was attacked in Swedish territorial waters on July 24. The crew was tied up and assaulted while masked pirates searched the cargo vessel. It was boarded between the Swedish islands of Oeland and Gotland in the Baltic Sea by the group of raiders who identified themselves as police officers, Swedish police said on July 31.

‘Explanations’

Police are assuming the vessel is under the control of hijackers, Ranta-aho said, adding that “there are other possible explanations.”

The European Commission, the 27-nation European Union’s executive arm in Brussels, said the Arctic Sea apparently reported a second attack off Portugal. It provided no further details.

The ship was scheduled to deliver a cargo of timber to Bejaia, Algeria, on Aug. 4, the Sovfracht maritime news service reported last week.

Solchart said yesterday it was unaware of a reported sighting off the Cape Verde islands. Russia’s envoy in Cape Verde, Alexander Karpushin, also denied the sighting report in comments broadcast on the state Vesti-24 television today.

To contact the reporters on this story: Maria Kolesnikova in Moscow at mkolesnikova@bloomberg.net Diana Ben-Aaron in Helsinki at dbenaaron1@bloomberg.net

Last Updated: August 15, 2009 11:55 EDT