The eight were sentenced to a pretrial detention center until late November by a court in Murmansk, a city in northwest Russia, on piracy charges, Russia's state-run news agency RIA Novosti reported Sunday.
The entire group of 30 people -- 28 activists and two freelance photographers -- could face 15-year prison sentences for their action, the report said.
Most of the activists were detained last week.
They were arrested for taking action against Gazprom's Prirazlomnaya rig in the Pechora Sea. The Russian Coast Guard seized the group's Arctic Sunrise protest vessel after firing warning shots.
Greenpeace said it was concerned about the potential for an oil spill in the harsh arctic environment.
Russian President Vladimir Putin said last week he was committed to protecting the arctic environment. He questioned the piracy charges filed against Greenpeace activists but backed their arrest on general security grounds.
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