The whereabouts of a Russian-manned cargo ship that vanished last month in the Atlantic remained in question Friday -- after a Russian envoy said that a reported sighting off the West African coast proved to be untrue.

French and Russian officials had said that the ship, the Arctic Sea, had been discovered off the coast of Cape Verde, and Russian ships were on their way to investigate, the Associated Press reported.

But a Russian news agency later quoted Alexander Karpushin, Russia's ambassador to Cape Verde, disputing that information about this ship, which had been carrying a load of timber and 15 Russian sailors.

"There was information that a cargo ship similar to the one being searched for was spotted 400 nautical miles north of the island of Santo Antao," Karpushin said after meeting with the head of Cape Verde's armed forces, according to Reuters. "However, this information did not prove to be true."

The Arctic Sea disappeared after passing through the English Channel on July 28. The Maltese-flagged freighter sent radio messages as it sailed along the coasts of France and Portugal, but then all contact was lost.

The ship's crew had reported a June 24 attack in Swedish waters by up to a dozen masked men, who they said tied them up, questioned them about drug trafficking, beat them and searched the freighter before leaving 12 hours later in a high-speed inflatable boat.

The alleged attack, unusual in itself, raised further concerns because it was not reported until the freighter had passed through Britain's busy shipping lanes and was heading out into the wide Atlantic. There have been fears that some of the attackers might still be aboard.

The Arctic Sea, which left from Finland on June 23, had been due to make port Aug. 4 in Algeria with its $1.8 million haul of timber.

Speculation on what might have happened to the ship has ranged from suspicions that it was carrying secret cargo — possibly narcotics — to theories about a commercial dispute. Security experts have been wary of attributing its disappearance to bandits, noting that piracy is almost unheard of in European waters.

The Associated Press contributed to this report.