Indonesia aims to unveil its $20 billion energy transition investment plan next month, an official said on Friday, days before the United Nations COP28 climate summit as Jakarta tries to resolve issues on funding and energy mix for the initiative.

Officials had initially planned to launch the Just Energy Transition Partnership (JETP) project in the middle of August, but this was delayed due to problems ranging from differences on funding details to the extent of Indonesia's reliance on coal for electricity.

The new target is for JETP plans to be released for public feedback on Nov. 1, with an official launch set for around Nov. 20, Paul Butarbutar, deputy secretary of Indonesia's JETP office, told reporters.

When asked whether the International Partners Group (IPG) - comprising of countries like the United States, Japan, as well as development banks and private lenders - is expected to agree on the investment plan by then, Butarbutar said: "We're going to agree on the content first, but funding, etcetera, are a different matter, a matter for later.".

He declined to provide further details.

Indonesia has agreed to cap and peak the power sector's carbon emissions at 290 million metric tons by 2030 under the JETP, following the IPG's commitment to provide financial support through a blend of equity investments, grants and concessional loans.

Indonesian officials have complained that Western countries are reluctant to finance early retirement of coal-fired power plants, which is needed to make way for renewable power plants.

Currently more than half of the electricity capacity in Indonesia, the world's biggest exporter of thermal coal, is fuelled by coal.

Finance Minister Sri Mulyani Indrawati has also asked for more grants to be included in the fund to reduce interest rates.

A member of the JETP technical working group has previously said the August delay was caused by the need to make sure that proposals reflect additional coal power plant capacity being built off grid by industrial firms, including remotely located nickel smelters. (Reporting by Bernadette Christina Munthe; Writing by Gayatri Suroyo Editing by Shri Navaratnam)