Brits Frank Hewetson, Iain Rogers and Kieron Bryan, as well as Jonathan Beauchamp of New Zealand, were charged late Monday, RIA Novosti reported.
Three others -- a Ukrainian, American and Canadian -- were charged earlier in the day, and three other activists were charged last week.
The charges come after Russian authorities said they would reduce the charges against the 30 Greenpeace members in custody. The activists were initially accused of piracy, which carries a maximum sentence of 15 years in prison. Hooliganism is punishable by a possible seven years.
The defendants were on board a Greenpeace ship when it was seized last month after some activists tried to climb the Gazprom oil rig to protest drilling in the Arctic.
Last week, a Russian court rejected the 30 detainees' requests for release on bail or house arrest.
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