In proceedings that Greenpeace said evoked Soviet-era scare tactics, activists from a ship used in the protest at an oil rig were led to court in Murmansk in handcuffs and held in cages for a series of hearings that ended early yesterday.
Twenty activists, a freelance photographer and a freelance videographer were ordered to be held for two months, while eight activists were ordered to be held for three days pending a further hearing.
All 30, who include six Britons, were detained last week aboard the icebreaker Arctic Sunrise, which was seized by Russian coast-guards in the Barents Sea after two activists tried to scale state-controlled Gazprom's Prirazlomnaya offshore oil platform.
Russia's federal Investigative Committee has termed the protest an attack and opened a criminal case on suspicion of piracy which is punishable by up to 15 years in jail.
Those held include the crew of the Arctic Sunrise, from deck hands and cooks to its American captain Pete Willcox.
Greenpeace International executive director Kumi Naidoo said: "These detentions are like the Russian oil industry itself, a relic from an earlier era."