10 a.m. update: YLE News reports the protesters have been removed from the ship.
HELSINKI -- Some 20 Greenpeace activists have climbed onboard an icebreaker in Helsinki harbor, locking themselves onto the ship and attaching banners to its sides, to protest oil and gas exploration in the Arctic Ocean.
Greenpeace says it boarded the Shell Oil Co. contracted Nordica as it was preparing to leave for the Alaska Arctic. The organization is calling on Shell to abandon its plans to open up the fragile waters for oil drilling.
Greenpeace says an oil spill off the Alaska coast would be detrimental for the environment and impossible to clean up because of the region's extreme weather.
In November, Arctia Offshore Ltd. agreed to provide two Finnish icebreakers, the Fennica and Nordica, to support oil and gas production operations on the northern Alaska coast in 2012 to 2014.