OSLO, Aug 25 (Reuters) - Oil companies in Norway must increase their exploration activity in remote regions like the Arctic Barents Sea for the country to find the remaining reserves of oil and gas beneath its oceans, the Norwegian Petroleum Directorte said in a report on Thursday.

Norway has pumped petroleum from its continental shelf for more than 50 years, but only half the potential resources have been produced so far, and about a quarter of the estimated oil and gas remains yet to be found, according to the agency. (Reporting by Nerijus Adomaitis, editing by Terje Solsvik)