The group of Greenpeace activists arrested in Russia during a protest against drilling in the Arctic face a three-month extension to their detention.
The organisation said Russia's investigative committee had announced it was applying for the extension against the 28 campaigners and two freelance journalists while it continues its investigations.
Greenpeace International executive director Kumi Naidoo said: "Our hearts break for our friends in jail and for their loved ones on the outside. We will fiercely resist this absurd attempt to keep those men and women in jail for a crime they did not commit.
"If the authorities succeed then we will appeal and ask for their release as soon as the court can schedule a hearing. This is a farce, it is an outrage that makes a joke of justice. It's time for the Arctic 30 to come home."
Greenpeace said hearings over the extension bid must be completed by November 24.
The 30 were detained on September 19 after the Russian authorities seized the Arctic Sunrise vessel.
Sir Paul McCartney has written a personal letter to Russian president Vladimir Putin calling for the release of Greenpeace activists.
Protests will be held at over 70 Shell petrol stations across the UK tomorrow as part of Greenpeace's campaign to free those arrested.