Japan’s third-largest refiner, Idemitsu Kosan, has announced its intention to buy British oil explorer Petro Summit Investment, a subsidiary of Japanese trader Sumitomo Corp.

Petro Summit produces approximately 5,000 barrels of oil equivalent a day (boed) on a rights ownership basis in the British North Sea.

The deal adds to the 28,000boed Idemitsu already produces in the Norwegian North Sea.

An Idemitsu company official declined to comment on the purchase price of the deal, but it is estimated to be several tens of billions of yen, reports Reuters.