Two Greenpeace activists occupied a drilling platform in southwestern Greenland Sunday to protest oil prospecting in the Arctic, causing the government to issue an angry reaction.

The activists, who arrived by rubber dinghy, climbed the 53,000-tonne "Leif Eiriksson", a rig due to begin drilling for oil for Scottish company Cairn Energy.

They placed themselves in a survival pod that now hangs from the platform 30 metres above icy water below, Greenpeace said.

"The two men are in this capsule with enough supplies for 10 days," said Birgitte Lesanner, Greenpeace spokeswoman in Denmark.

The event took place early Sunday morning, about 100 kilometres (60 miles) off the coast of Greenland's capital, Nuuk.

The platform was on its way to its field of operations where two seperate drilling explorations are to take place before December, when Arctic water begins icing over.

One of the militants, calling himself Luke, said he was "proud to have managed to attach my pod above water" and to "help stop this folly".

"Cairn Energy plays dangerously with Greenland's nature," said Greenpeace in a statement, deploring that the Scottish oil company stayed "deaf to calls by environmental organisations, fishermen and warnings by Canada and the United Kingdom against drilling in the Arctic."

Greenland authorities condemned the action "vigorously", calling it illegal and a "flagrant violation of international law".

"Greenpeace is acting cynically, at the expense of the legitimate rights for those less advanced to develop economically," industry minister Ove Karl Berthelsen in a statement, labelling Sunday's action a stunt to "attract media attention".

Greenland, an overseas territory of Denmark, is looking to oil prospecting as a way to ensure its economic independence.

Cairn Energy has told Greenland authorities that it will continue moving its platform towards the agreed drilling point and it has not excluded asking police to evict the two activists.