The head of Indonesia's state energy company said Wednesday that the company has given Exxon Mobil Corp. (XOM) "enough time" to begin boosting production in the giant Cepu oil and gas block, suggesting a risk that it may push for changes in a contract to operate the area.

Pertamina Chief Executive Karen Agustiawan said that "this is the time that the production needs to be onstream" and that whether the Indonesian company becomes the operator or not, "we have to have a say." She said that "we have given Exxon enough time." Her comments came in response to a question during an interview with Dow Jones about whether Pertamina would demand to change the contract for operating the block.

Cepu, operated by Exxon's subsidiary Mobil Cepu Ltd., started in December 2008 but shut in April due to pipeline problems. Mobil Cepu has previously said it aims to ramp up production to 15,000 barrels a day by October. Cepu is expected to eventually produce around 160,000 barrels a day.

An Exxon spokeswoman declined to comment, citing company policy. She said in an e-mail that Mobil Cepu Ltd. and its partners "remain focused on safely and efficiently developing Cepu oil and gas resources, and in doing so supporting Indonesia's priorities in energy production."

As for a decision on which block Pertamina will offer Total SA (TOT) in exchange for a 15% stake in its offshore Mahakam gas block the Indonesian company hopes to buy, Agustiawan said that it won't be made "before we sit down and see the upside potential of what is left in Mahakam." She expects that evaluation to be complete by the end of October.

-By Siobhan Hughes, Dow Jones Newswires; 202-862-6654; Siobhan.Hughes@dowjones.com

(I-Made Sentana contributed to this article.)