Indonesian state oil and gas producer PT Pertamina will acquire a 15% in the Mahakam gas block from France's Total SA (TOT) this year, possibly via an asset swap in which Total would gain a stake in one of Pertamina's concessions, the Indonesian firm's chief executive said Monday.

Total agrees to the deal but has asked Pertamina to exchange a stake in one of its own blocks, CEO Karen Agustiawan told reporters.

"We understand this, as no oil company wants to lose (part of) its portfolio," she added. Her comments came following a trip to Paris last week when officials from Pertamina and Total met to discuss Pertamina's plan to buy part of Mahakam, which is located in eastern Indonesia and is one of the Southeast Asian nation's largest gas deposits.

Agustiawan said Pertamina has yet to decide which asset might be exchanged for the Mahakam stake. She gave no further details on the possible timing of the purchase.

Officials at Total's France headquarters couldn't immediately be reached for comment.

-By Deden Sudrajat and Reuben Carder, Dow Jones Newswires; 62 21 3983 1277; Reuben.Carder@dowjones.com