MOSCOW, September 30 (RAPSI) - Investigators have regarded the actions of Greenpeace activists suspected of having committed acts of maritime piracy as a real threat to the Prirazlomnaya drilling rig's employees, Russia's Investigative Committee reported Monday.

The Arctic Sunrise ship was seized by Russian border guards on September 19 in international waters, within Russia's exclusive economic zone, a day after two Greenpeace activists scaled the Prirazlomnaya drilling rig in the Pechora Sea, the southeastern part of the Barents Sea. Greenpeace claimed that the ship was held under armed guard.

Russian investigators said the vessel was involved in maritime piracy, a crime punishable by up to 15 years in prison, and that an investigation would be conducted to consider the allegations. The ship is expected to arrive in the Russian port of Murmansk on Tuesday.

Media reports claim that some 30 people, including six Britons and one American, were on board the vessel. All of them have been detained until November 24.

At present, investigators are carrying out an inspection aboard the ship. Documents in a foreign language and some equipment have been already impounded. All persons involved in the case may be officially charged in the nearest time.

The platform, owned by Gazprom Neft Shelf, a subsidiary of Russian energy giant Gazprom, is the first ice-resistant stationary oil platform in the world set to produce offshore Arctic oil.

Greenpeace and other environmental groups oppose drilling for oil in the Arctic because they say that it is currently impossible to sufficiently clean up potential oil spills in the region, and that such drilling cannot be economically viable without state subsidies.