Greenpeace New Zealand says the downgrading of piracy charges against two New Zealanders is no cause for celebration and the Government must do more to free them.
Russia has dropped piracy charges against 30 people involved in a Greenpeace protest over Arctic oil drilling, replacing them with lesser charges.
New Zealanders Jon Beauchamp and David Haussman are among the group arrested during a protest from a Dutch-flagged ship at an offshore oil platform belonging to Russia's state-controlled energy firm Gazprom in the Barents Sea in September.
Russia's federal Investigative Committee says the charges have been downgraded from piracy, which carries a maximum jail sentence of 15 years, to hooliganism, which is punishable by up to seven years in prison, Reuters reports.
Greenpeace's chief policy adviser Nathan Argent said on Thursday the environmentalist group will contest the hooliganism charges in the same way it has contested the piracy ones and the downgrade is no cause for celebration.
"As far as we're concerned they're both fantasy. In fact, the charge of hooliganism again has no grounding in law, because you can only charge someone with hooliganism on Russian territory. And it is clear that were actually in international waters."
Mr Argent says Mr Haussman and Mr Beauchamp are comfortable in their prison in Murmansk and have been in touch with their families. But he has heard worrying things about their treatment, such as a lack of exercise and a lack of heating.
Mr Argent says the New Zealand Government needs to follow in the footsteps of others and actively encourage Russia to free the activists. He says Prime Minister John Key should join other world leaders in calling for a very swift resolution to the situation.
New Zealand's Ministry of Foreign Affairs and Trade says it is still seeking a Russian confirmation the charges have in fact been downgraded.
A spokesperson says consular staff last visited Mr Haussman and Mr Beauchamp on 17 October and they remain in good spirits. New Zealand's embassy in Moscow is continuing to provide assistance.
A spokesperson for Greenpeace in the Netherlands, Kees Kodde, told Radio New Zealand's Morning Report programme the organisation will now reapply for the activists to get bail. The activists have been in detention for five weeks.