UK activists are among a group jailed in Russia following a protest against Arctic oil drilling, Greenpeace has said.
A group of 29 activists, including six Britons, and a photographer were held last week when armed Russian officials boarded their vessel near to oil company Gazprom's platform.
The ship and protesters have been taken to the port of Murmansk, and Russian authorities said they were investigating charges of piracy, which carry a jail term of 10 to 15 years.
A Russian court has refused bail and jailed the photographer and a number of the activists for two months pending the investigation. They have not been charged.
John Sauven, executive director of Greenpeace UK, said the decision "is a total over-reaction".
"Our focus now is on supporting the families of the UK activists being held and galvanising public opinion to bring pressure on the Russian authorities to release all those detained."