Cairn Energy has discovered gas off the coast of Greenland, a sign that could lead to a possible oil discovery.
Edinburgh-based Cairn, the only firm to have been given permission to drill for oil offshore in Greenland, said it had early indications of a working hydrocarbon system in Baffin Bay.
But environmental campaigners have raised concerns in the wake of BPs Gulf of Mexico oil spill disaster.
Greenpeace said the announcement was grave news.
The group says it threatens the fragile Arctic environment, and has sent a protest ship to Baffin Bay.