Some 4,000km from Japan, on a verdant, mangrove-lined island in south-eastern Bangladesh, sits one of the biggest and most controversial tests of Tokyo’s commitment to help phase out fossil fuels. Thanks to low-interest loans from the Japan International

Cooperation Agency, Bangladesh is currently building the Matarbari coal plant: a power complex set to be completed by 2024. And JICA, a government body, has been considering funding an expansion to the 10-year-old project, known as Matarbari Phase 2 — despite, earlier this year, saying it would work with Bangladesh “to promote a low- or zero-carbon transformation” of its energy economy.

This debate around the Matarbari plant embodies the tensions in Japan’s fossil-fuel policies. Its financing of coal power in developing countries risks falling out of step with moves to promote renewable energy at home and abroad.

In Bangladesh — a low-lying country highly vulnerable to the effects of climate change, such as rising sea levels and erratic rainfall — the government of prime minister Sheikh Hasina has been backing coal to meet energy needs.

However, official enthusiasm for mega-projects such as Matarbari is waning as renewable alternatives become cheaper. Hasina’s government last month scrapped 10 of the coal-power plants it had planned. While the mooted Matarbari Phase 2 project was not officially among them, analysts say it is looking less and less viable.