"Cairn is pleased to announce the acquisition of Agora Oil & Gas AS (Agora) subject to regulatory approval, a private Norwegian company with non-operated, exploration, appraisal and development assets in the United Kingdom and Norwegian North Sea," the group announced in a statement.
Edinburgh-based Cairn, which has been transformed in recent years by successful exploration projects in India, has since turned its focus to offshore Greenland and elsewhere.
Agora, which was founded in 2009 to explore mature parts of the North Sea region, is currently owned by its management, investment fund RIT Capital Partners and the Rothschild family.
"Cairn Energy announced the acquisition of Agora Oil & Gas this morning as it seeks to broaden its portfolio of exploration and development assets beyond Greenland and the eastern Mediterranean," added analyst Gerry Hennigan at Goodbody Stockbrokers in Dublin.
Cairn had revealed last month that net profits rocketed last year, boosted by the sale of most of its Indian division to Vedanta Resources.
Profits after taxation hit $4.1 billion last year, compared with $794.3 million in 2010.