Activists have planted a flag at the North Pole along with millions of signatures calling for the Arctic to be declared a global sanctuary protected from oil drilling, lobby group Greenpeace said on Monday.

Expedition members cut a hole in the ice and lowered the "flag for the future" onto the seabed along with a titanium-glass capsule containing 2.7 million signatures against the exploitation of the pristine Arctic.

The flag, atop the titanium-ringed glass sphere, was lowered near where a Russian mini-submarine in 2007 controversially planted a Russian flag at the bottom of the Arctic Ocean.

The Greenpeace expedition included Hollywood actor Ezra Miller, indigenous Sami MP Josefina Skerk from Sweden and Renny Bijoux from the Seychelles, all of who trekked for a week to reach the geographical North Pole, a statement said.

"We're here to say this special area of the Arctic belongs to no person and no nation, that it is the common heritage of everyone on Earth," said Sami Parliament member Skerk, 26.

Amsterdam-based Greenpeace says the Arctic is under threat from climate change, oil companies, industrial fishing and shipping, with oil giants such as Shell and Gazprom moving in as nations lay claim to areas previously covered by ice.

Shifting ice and dwindling supplies meant that the expedition members had to hitch a lift with a helicopter for one of the final legs of their journey.

The Arctic seabed is thought to hold about 90 billion barrels of oil and 30 percent of the world's undiscovered gas resources, according to the US Geological Survey.

"As temperatures rise and the ice retreats, the oil companies are moving in. They want to drill for the fossil fuels that caused the melting in the first place. It's madness, we have to stop them," said Miller, star of the 2011 film "We Need to Talk About Kevin".

"My country would literally disappear if sea levels rise. I have come to the North Pole from the Seychelles to plant this flag because what happens in the Artic matters to me, people from my country and everyone across the world," Bijoux said in the Greenpeace statement.

The flag was designed by Malaysian schoolgirl Sarah Batrisyia in a competition judged by British fashion icon Vivienne Westwood.