Greenpeace activists have climbed onto a rig in Baffin Bay off Greenland where Cairn Energy is undergoing test drilling and last week said it had found clear signs of hydrocarbons.

According to the reports the activists, who have previously been on board the Greenpeace vessel Esperanza near the rig, have encroached on a 500 metre no-approach zone imposed by the authorities, and are attempting to stop the rig from drilling by climbing up inner rig supports.

Greenpeace says that drilling will cease as safety rules require drilling to stop if a safety zone has been encroached upon.

The activists are said to have attached tents to the rig and have supplies for several days.

The authorities have previously said that any encroachment on the 500 metre no-approach zone would result in the arrest of the Esperanza's captain.

It appears that Greenpeace is hoping to delay drilling long enough so that Cairn Energy is unable to finish its task before the end of September when ice begins to enter Baffin Bay.