Russian guards arrested 30 Greenpeace members in September after boarding the group's ship, the Arctic Sunrise, which carried a Dutch flag.
Greenpeace members had attempted to board a Russian oil rig operated by Gazprom subsidiary Gazprom Neft Shelf in the northern Pechora Sea.
The majority of the 30 Greenpeace members -- from 18 countries -- were remanded for two months last week, RIA Novosti reported.
"Today, the investigation has begun the process of bringing charges against the suspects over the case into the attack on the Prirazlomnaya oil rig," an Investigative Committee member said Wednesday.
Russian President Vladimir Putin said the activists "are not pirates," but they contravened international laws.
Greenpeace representatives said the protest was peaceful and legal.