Russian authorities arrested all 28 activists and two journalists for a September protest against a Russian oil rig operating in arctic waters. They were charged with piracy by the Russian courts.
Russian Foreign Minister Sergei Lavrov said the incident is an internal matter and outside parties shouldn't intervene, Russia's state-run news agency RIA Novosti reported Tuesday.
A Dutch court started arbitration proceedings to settle the issue under international law and Brazilian President Dilma Rousseff said she'd intervene on the behalf of Brazilian activist Ana Paula Maciel. The U.S. State Department and former U.S. Secretary of State Hillary Clinton expressed concern over the fate of U.S. nationals involved in the fray.
Lavrov didn't single out any particular country in his complaint. The activists remain behind bars until their Nov. 24 hearing.
Greenpeace said it intervened to show its concern over the threat to the environment posed by arctic drilling.