The Murmansk Regional court ruled to deny bail to three of the 30 people arrested when their ship was seized in the Arctic Ocean's Pechora Sea near an oil drilling rig.
Peter Wilcox of the United States, Camila Speziale of Argentina and David John Hausmann of New Zealand were returned to jail Monday, bringing the number of those arrested and denied bail to nine, the Russian news agency RIA Novosti reported.
"The lawyers are determined to appeal all actions of the court and investigators," an unidentified Greenpeace representative told the news agency ITAR-Tass.
Russian authorities suggested the detainees may be also charged with drug charges, claiming they found opiates aboard their ship, RIA Novosti said.
Greenpeace called the claims exaggerated, saying the Russian government is likely referring to "medical supplies our ships are obligated to carry under maritime law."