MOSCOW, August 25 (RIA Novosti) - Allegations that the Arctic Sea merchant ship may have been involved in illegal operations will be probed, Russia's chief investigator said on Tuesday.

Press speculation on the mystery surrounding the Arctic Sea's disappearance has been rife with some media saying the Russian authorities are trying to cover up a smuggling or trafficking operation. Moscow-based columnist Yulia Latynina speculated that the vessel was secretly shipping arms via Algeria to a rogue state such as Iran or Syria.

Other reports have suggested that the Arctic Sea was hiding a second, smaller vessel while sailing off Sweden's east coast.

Russian envoy to NATO Dmitry Rogozin has dismissed such allegations as "fantastic" and "ridiculous."

"We do not rule out that it may have carried more than just sawn timber," Alexander Bastrykin, head of the Investigations Committee at the Russian Prosecutor General's Office, said in an interview with Rossiiskaya Gazeta that will be published on Wednesday.

He confirmed that the Arctic Sea crewmembers were in custody and being questioned.

"This is part of the reason why we have detained the crew: It has to be established if some [of them] have been involved in the events."

He added that the bulk carrier could be impounded for a thorough search.

"I do not rule out that we will hold the vessel until trial as material evidence," he said.

The defense lawyer for two of the alleged hijackers arrested aboard the Arctic Sea last week said on Tuesday there has been no mention of arms trafficking in the court files.

Konstantin Boronovsky stressed, however, that he could only cite the files that he had actually read.

Last Friday, Moscow's Basmanny District Court remanded in custody eight unemployed men from Estonia in the case. All eight deny accusations of piracy and hostage-taking.

Boronovsky's clients formally appealed their arrest on Tuesday amid speculation that they may have been in cahoots with the alleged hijackers.

Meanwhile, some media reports have dismissed the hijacking theory as a ploy.

The Maltese-flagged vessel, which had been missing in the Atlantic for more than two weeks, was discovered off Cape Verde last Monday by a Russian warship.