Melbourne- BHP Billiton has agreed to sell its Pakistan gas business to a local firm, a unit of the Hashoo Group, for an undisclosed sum, the global miner said today.

"The transaction is subject to regulatory approval and is expected to close in the fourth quarter of 2015," BHP said in an emailed statement.

BHP, operator of the Zamzama gas field and processing plants, has been looking to sell its 38.5 percent stake for some time, as it works to simplify its petroleum business to focus on the United States, Australia and Trinidad and Tobago.

It sold its Liverpool Bay oil and gas fields off the Irish Sea in 2013 and has been looking to sell its Algerian assets.

Gas and condensate from Zamzama are sold within Pakistan. The other owners of the field are Italy's ENI SpA, Premier Oil, Kuwait's KUFPEC, and the Pakistan government.