Activists of the environmental group Greenpeace who boarded an oil rig off the coast of Greenland in a bid to disrupt an imminent drilling campaign by Cairn Energy PLC (CNE.LN) have been removed by Greenland authorities, Cairn Energy said Thursday.

"The authorities in Greenland took the action to ensure the safety of those involved in and around the drilling operations," said the Edinburgh-based oil and gas explorer, adding that there had been no impact on its schedule as a result of the protests.

Activists boarded the semi-submersible drilling vessel the Leiv Eiriksson, owned by Ocean Rig, around 100 miles off the coast of Greenland, at the weekend.

Cairn is currently the only company planning to drill in the region after disappointing results from a campaign last year. But Greenpeace has said if it strikes oil this summer it will spark an oil rush that would devastate the fragile Arctic environment.

Greenland's government said Monday that Greenpeace's actions were "illegal" and the protesters faced removal by police if they continued to occupy the rig.

Greenpeace wasn't immediately available for comment when contacted by Dow Jones Newswires Thursday.

However, the group tweeted earlier "activists arrested and pod captured--but this is not the end of our campaign to keep risky oil drilling out of the Arctic. We salute the brave stand made by [activists] Hannah and Luke in their four-day Arctic oil protest."

Cairn's 2010 Greenland drilling found traces of oil and gas the company said were encouraging, but it failed to make any commercial discoveries. Investors reacted with disappointment to the lack of a discovery and to the fact that Cairn fell short of its target of drilling four wells.

Delays, caused mainly by geological complications, meant Cairn only completed two wells and drilled a third to less than its target depth.

Greenpeace protesters also halted drilling operations for around 40 hours in early September by attaching themselves to the bottom of the rig. Cairn said the impact of the delay this wasn't a factor in missing the target of drilling four wells and that the 40 hour stoppage was immaterial to operations.

Cairn estimates its target reservoir could contain up to 3.2 billion barrels of oil equivalent. The area is largely unexplored and it puts its chances of a commercial hydrocarbon discovery at 10% to 20%.

Cairn said it "respects the rights of individuals and organizations to express their views in a safe and peaceful manner but would be concerned with anything that presents a safety risk for those involved and the operations."

Cairn maintains that its drilling offshore Greenland is safe. It has the full permission of the Greenlandic authorities for its activities.

At 0812 GMT, Cairn Energy shares were down nine pence, or 2.15%, at 428p.