Four Britons are among several people charged with piracy by Russian investigators after a protest against Arctic oil drilling.
Freelance videographer Kieron Bryan, communications officer Alexandra Harris and activists Anthony Perrett and Philip Ball are all facing up to 15 years in prison if found guilty.
Those also charged include Brazilian crew member Ana Paula Alminhana, Russian activist Roman Dolgov, Finnish activist Sini Saarela, and Dima Litvinov, an activist with Swedish and US citizenship.
A total of 30 Greenpeace campaigners were detained as their ship circled near the Prazlomnaya oil platform in the Pechora Sea, after some activists attempted to get on to the platform two weeks ago.
Greenpeace International executive director Kumi Naidoo condemned the charges, saying: "It is an extreme and disproportionate charge.
"A charge of piracy is being laid against men and women whose only crime is to be possessed of a conscience. This is an outrage and represents nothing less than an assault on the very principle of peaceful protest."
The group of activists had already been ordered to spend two months in custody in the northern city of Murmansk, pending an investigation.
The other Britons being held are cameraman Philip Ball, communications officer Alexandra Harris, logistics co-ordinator Frank Hewetson, activist Anthony Perrett and engineer Iain Rogers.
The platform, the first offshore rig in the Arctic, is owned by Russia's state-controlled energy giant Gazprom.
Oil giants ExxonMobil, Eni and Statoil, along with other Norwegian firms, plan to drill for oil in Russia's Arctic waters in the coming months.
Greenpeace has warned an oil spill would cause significant environmental damage and warns of fossil fuel extraction contributing to climate change.
Russian President Vladimir Putin had said he did not think the protesters were pirates but defended their detention, saying that coast guards had no way of knowing who they were.