LONDON, Nov 2 (Reuters) - Indonesia could phase out coal-fired power plants by 2040 if the country gets sufficient financial help from the international community, its finance minister told Reuters on Tuesday. The Southeast Asian archipelago is the world"s fourth most populous country and eighth biggest greenhouse gas emitter with coal accounting for around 65% of its energy mix. It is also the world"s biggest coal exporter. Sri Mulyani Indrawati told Reuters during her visit to the Scottish city of Glasgow for the COP26 conference that Indonesia will on Wednesday announce detailed plans to move to cleaner energy, with the phase-out of coal being the key issue. Previously, Indonesia said it planned to phase out coal for electricity by 2056, as part of a plan to reach net zero carbon emissions by 2060 or earlier. "If we are going to put forward until 2040, then we need to have funding to retire coal earlier and to build the new capacity of renewable energy," Sri Mulyani said. "That is exactly what has now become the core issue and I"m now as the finance minister calculating what does it mean to retire coal earlier. How much does it cost us?," she said. British Prime Minister Boris Johnson last week told the UK parliament that President Joko Widodo had said Indonesia is going to bring forward its target to phase out coal to 2040. Indonesia had not previously confirmed such a plan. Sri Mulyani told Reuters that meeting such a target was conditional on getting financial help from multilateral institutions, the private sector and developed countries. "For Indonesia, retiring coal early will cost us, then it will also cost the people, it will cost the industry," she said. "If this is all supposed to be financed from my taxpayers" money, that won"t work. The world is asking us, so now the question is what the world could do to help Indonesia." She said the plans due to be announced on Wednesday moved Indonesia"s climate targets beyond "rhetoric" into the technical details and that the Asian Development Bank and other financial institutions were "very excited" with their ideas. Indonesia has said it will need to invest $150 billion to $200 billion per year in low carbon programmes over the next nine years to meet its goal to reach net zero carbon emissions by 2060 or earlier.