Greenpeace vessel Arctic Sunrise is moving through the North Sea to protest work planned by the U.S. and Russian oil companies at the East-Prinovozemelsky oil field. Russia law requires a permit for travel through the northern arctic sea route, though Greenpeace's application was turned down.
The advocacy group told Russia's state news agency RIA Novosti on Saturday it was accepting the risk of operating in the region without a permit.
The field is in the Kara Sea near Russia's northern Yamal Peninsula. Exxon Mobil and Rosneft last year signed a sweeping deal that included development in parts of the Black Sea and the South Kara Sea in the Russian arctic. There may be as much as 85 billion barrels of oil in the area.
Greenpeace said it was determined to stage a peaceful protest against arctic drilling. Critics say it would be difficult to respond to a major spill in pristine arctic waters.