A British freelance videographer and a Greenpeace activist have been charged with piracy by Russian state prosecutors after a protest at an Arctic oil rig, the environmental campaigning group has said.
Greenpeace said the "extreme and disproportionate" charge - which carries a maximum jail sentence of 15 years - had been laid against crew member Ana Paula Alminhana from Brazil and freelance videographer Kieron Bryan from the UK.
The campaigners said they expected charges to be brought against other activists.
Greenpeace International executive director Kumi Naidoo condemned the move.
" A charge of piracy is being laid against men and women whose only crime is to be possessed of a conscience," he said.
"This is an outrage and represents nothing less than an assault on the very principle of peaceful protest. Any claim that these activists are pirates is as absurd as it is abominable.
"It is utterly irrational, it is designed to intimidate and silence us, but we will not be cowed."
The Russian coastguard seized a Greenpeace ship and all 30 people - including six Britons - on board following the September 18 protest at an offshore platform in the Arctic owned by Russian state-controlled energy giant Gazprom.
Mr Naidoo said the "courageous" crew of the Greenpeace ship, the Arctic Sunrise, had protested at the Gazprom rig because they felt "compelled to bear witness to the slow but unrelenting destruction of the Arctic".
"The ice is retreating, oil companies are moving north to drill for the fuels that are driving that melting, species are at risk, including our own," he said.
Greenpeace said two activists had tried to climb the side of the drilling platform and hang a banner. They said Russian security services had abseiled from a helicopter onto the deck of the Arctic Sunrise and seized the ship at gunpoint.
The boat and protesters were taken from the Arctic's Pechora sea, near to Gazprom's platform, and transferred to the port of Murmansk.
Britons Frank Hewetson, a long term activist with the environmental group, and Anthony Perrett have already been remanded in custody on suspicion of piracy following court appearances.
Mr Bryan's parents have said they are ''extremely worried'' about their 29-year-old son, who is from Devon .
Andy and Ann Bryan, from Shebbear in Devon, said: ''Our son is a very kind, caring individual and environmental issues have always been very close to his heart.
"He would sympathise with the cause but he was simply there doing his job as a freelance videographer."
Mr Bryan, a freelance filmmaker and videographer, previously worked at The Times. He was hired on a short-term contract by Greenpeace to document its work on Russian oil exploration in the Arctic Circle.