MOSCOW (AFP) - Russia is moving the imprisoned crew of Greenpeace's Arctic Sunrise protest ship from their jail in the Arctic Circle city of Murmansk to St Petersburg, the organisation announced on Friday, quoting information from diplomats.

The 30 crew, mostly foreigners, arrested in September after protesting oil exploration in the Barents Sea, "are being moved from a detention centre in Murmansk to a jail in Saint Petersburg", Greenpeace said in a statement.

"We had various diplomats confirm this information," said spokesman Dannielle Taaffe.

The crew, which includes activists and journalists, have stayed since September under pre-trial arrest in a jail in Murmansk, and have complained of cold cells and lack of suitable clothing and food.

They were detained and charged with piracy after their Arctic Sunrise ship was boarded by Russian coastguards in September.

Last Wednesday, the Investigative Committee said in a statement that it had reclassified the crime as hooliganism, a lesser charge, but Greenpeace on Friday said that the activists never received official documents that would formally lift the piracy charge.

"Essentially, right now all 30 people have two charges," said spokesman Maria Favorskaya. While piracy carries a punishment of up to 15 years in prison, hooliganism can be punished by a maximum of seven.

Investigators in Murmansk previously said that the entire high-profile probe is being handled from Saint Petersburg, rather than by the local Investigative Committee.

Several activists in mid-September attempted to scale Russia's Gazprom oil platform in the Pechora Sea, part of the Barents Sea, in protest of its exploration in the Arctic.

The Greenpeace ship went under control of Russian authorities after it was boarded on September 19. It was towed to the Murmansk port. Greenpeace says the authorities had no right to arrest the Dutch-flagged ship in international waters.

The Netherlands have launched legal action against Russia, with first hearing scheduled for next Wednesday at the International Tribunal for the Law of the Sea.