Cooper Energy has announced that completion of the previously announced sale of its 55% interest in the TangaiSukananti KSO in South Sumatra Basin, Indonesia, would be delayed as regulatory approval has not yet been secured.

The $4.3m sale to Canadian oil and gas company ACL International was announced last month and is expected to occur after 29 July.

Cooper Energy signed an agreement with ACL through its wholly-owned subsidiary Bow Energy International and a Singapore-based oil and gas company Lamara Energy for the sale of its interest.

The agreement is subject to regulatory, as well as joint venture approvals.

"The $4.3m sale to Canadian oil and gas company ACL International was announced last month and is expected to occur after 29 July."

Since Cooper did not secure regulatory approval, it considers that completion may not take place by 29 July as anticipated.

Cooper expects to obtain the regulatory in due course and plans to work to support the outcome.

The company said that the deal will complete its withdrawal from Indonesia, which was announced earlier this year as part of its strategy to specifically focus on Australia and the Gippsland Basin gas projects.

Cooper completed the sale of its exploration assets Indonesia on earlier last month for $9.07m.

Cooper Energy managing director David Maxwell said earlier that the company delivered a 260% increase in proved and probable oil reserves in the KSO, Indonesia.

Production has also been increased around 13 times from about 60 barrels of oil per day (bopd) before it was closed under previous ownership to the current rate of about 800bopd.