An undated photo shows the Maltese-registered, Finnish-chartered cargo vessel Arctic Sea that mysteriously disappeared off the coast of France on July 29. (Sovfracht/Reuters)

A Russian-manned freighter that went missing last month in the Atlantic Ocean has been located and its crew has been taken aboard a Russian naval vessel, media reports quoted the country's defence minister as saying Monday.

The Arctic Sea and her Russian crew, who were bound for Algeria from Finland, were last heard from sailing through the English Channel on July 28.

Russian news agencies quoted Russian Defence Minister Anatoly Serdyukov as saying he informed President Dmitry Medvedev that the 15 crew members of the Arctic Sea were alive and taken off the ship near the Cape Verde islands.

"The crew are all alive and well," Serdyukov said.

He did not give details about what happened to the ship, saying the full story could be made public later Monday, according to the agencies.

Over the weekend, Finnish investigators said a ransom demand had been received for the return of the Maltese-flagged vessel.

The crew had said they were attacked in Swedish waters four days before the ship disappeared, but there has been no confirmation that the ship was actually seized.

The crew reportedly told authorities in Malta that they were tied up, beaten and locked away while men searched the ship.

They said the raiders eventually left empty-handed, and the 4,000-tonne vessel sailed on with its $2-million load of timber.

The information gathered by Maltese authorities was passed to the Russian Foreign Ministry, which called the Swedish government looking for answers.

Swedish police said the ship was probably attacked by pirates or criminals, but not by its officers.

With files from The Associated Press