A Russian court in Murmansk has ordered the last eight Greenpeace protesters who tried to scale an Arctic oil drilling platform to stay in jail two more months.
Twenty-two other suspects were ordered last week to remain behind bars while officials investigate alleged piracy.
The activists from the Greenpeace ship Arctic Sunrise tried to board the Russian state-owned Gazprom platform almost two weeks ago.
Armed security guards stopped them, believing the activists may have been pirates.
Russian President Vladimir Putin already has said the 30 are not pirates, but he says they broke international law and put the oil platform workers and themselves in danger.
Greenpeace says the platform poses a severe risk to Russia's Arctic coastline if there should be an oil spill.
The 30 Greenpeace members include activists from Russia, the United States, Brazil and Britain.