Russia's top investigator said it is possible a freighter embroiled in a high-seas mystery was carrying more than just timber, the Interfax news agency reported Tuesday.

The reported comment by federal Investigative Committee Chief Alexander Bastrykin is the first suggestion by a Russian official that the Arctic Sea could have been carrying a sensitive cargo — a suspicion raised by observers who followed the weekslong saga.

The Maltese-flagged freighter left Finland on July 21 with a load of timber, but then seemed to vanish in the Atlantic. Russia's defense minister announced last week that the Arctic Sea had been found off West Africa and that it had been hijacked.

Eight people who were aboard — including citizens of Russia, Latvia and Estonia — have been jailed in Moscow and face trial on charges that include piracy.

The developments have sparked speculation that the ship could have been carrying a secret cargo that somebody wants to keep under wraps. Suspicions have been heightened by the involvement of the Russian navy, the slow trickle of information and claims that news media were fed bogus information about the ship.

In an interview to be published Wednesday in the government newspaper Rossiiskaya Gazeta, Bastrykin was quoted as saying, "we do not rule out the possibility that they might have been carrying not only timber," according to Interfax.

"This is why we need to examine the vessel — so that there are no dark spots in this story," Bastrykin was quoted as saying.

More than a week after the Arctic Sea's departure from Finland, Swedish police said they had received a report that masked men had raided the ship in the Baltic Sea and beaten the crew before speeding off 12 hours later in an inflatable craft.

The freighter gave no indication of any difficulties or change in its route during radio contact while passing through the English Channel on July 28. Signals from the ship's tracking device were picked up off the French coast the next day.

A day later, a Russian Navy warship mounted an operation to retrieve the 15 Russian crew members and detain the eight suspected hijackers.

The suspected hijackers have denied guilt, claiming they were environmentalists who had sought refuge aboard the Arctic Sea after deserting their own vessel in a storm.