Piracy charges have been dropped against 30 Greenpeace activists, including two New Zealanders, being held in Russia.
Officials have replaced the charges with ones of hooliganism, which carry a maximum penalty of seven years in prison, instead of the 15 for piracy.
A statement by Russia's main investigative agency announced the change in charges this morning.
The environmentalists, including Kiwis Jonathan Beauchamp and David Haussmann, were arrested in September after Russian authorities boarded their vessel The Arctic Sunrise in international waters.
The 28 Greenpeace activists, a freelance photographer and a freelance videographer, were protesting against drilling for oil in Arctic waters, and had focussed their attentions to a drilling platform owned by gas giant Gazprom. Two people had tried to climb onto the platform and hang a banner.
The plight of Mr Beauchamp and Mr Haussman was raised by Prime Minister John Key when he met Russian President Vladimir Putin at APEC earlier this month.
Vladimir Chuprov of Greenpeace Russia said the new charges were still "wildly disproportionate", and the Arctic 30 are "no more hooligans than they were pirates".
"It represents nothing less than an assault on the very principle of peaceful protest," he said in a statement.
"Those brave men and women went to the Arctic armed with nothing more than a desire to shine a light on a reckless business. They should be with their families, not in a prison in Murmansk."
He said Greenpeace will contest the "trumped up charge" of hooliganism as strongly as it protested the piracy charges.
"They are both fantasy charges that bear no relation to reality. The Arctic 30 protested peacefully against Gazprom's dangerous oil drilling and should be free," he said.
Mr Chuprov said Russia's main investigative agency, The Investigative Committee, has also suggested it may charge some of the environmentalists with use of force against officials, which carries a maximum 10 year prison sentence.
He called for the immediate release of the 30 prisoners.
Greenpeace Netherlands spokesman Kees Kodde said it was the Dutch Government which had launched legal proceedings against the Russian Government.
"Netherlands is taking Russia to court because Russia took the vessel which was a Dutch ship and detained the activists," he told Radio New Zealand.
"I think Netherlands is continuing with the case, because they launched a case last Monday at the International Tribunal for the Law of the Sea."
What has happened with the charges wouldn't change much as the "ridiculous" accusation of hooliganism remained, which carried a maximum sentence of seven years imprisonment, Mr Kodde said.
"In fact, the punk group Pussy Riot, who are now rotting in a Russian jail, were also accused of hooliganism.
"Although the charge of piracy has been dropped, this is still a very disproportionate accusation."
Greenpeace would continue to fight the charges, Mr Kodde said.
Greenpeace had existed for 42 years and while they were known to protest and hang banners, they never used violence or force, he said.
"This accusation is totally unfounded, and we hope that the court will determine so."
The prisoners' families had not been able to receive visitors and a lot of letters sent to them were withheld, Mr Kodde said.
"They're in a really bad situation."