The move is a part of Indonesia’s efforts to upgrade refineries to meet the growing energy demands.

The Jakarta Post quoted Pertamina refining, trading and marketing director Ahmad Bambang as saying to reporters: "We are aiming for Dec. 10, coinciding with Pertamina’s anniversary, to sign MoUs [memorandums of understanding] with four investors for our refinery upgrades.

The county is considering to upgrade refineries located in Cilacap, Central Java; Balikpapan, East Kalimantan; Balongan, West Java; and Dumai, Riau, Bambang said.

Meanwhile, Pertamina is currently negotiating with the four investors to launch joint ventures to ensure crude supplies for refineries in Indonesia.

Bambang said: "We’re looking for partners to develop refineries and to guarantee the security of supply.

The refineries upgrade program, which would be performed in two folds, is expected to take about five years to complete.

In addition to operating six refineries in Indonesia, Pertamina operates refineries in Kasim in West Papua and Plaju in South Sumatra.