Coal accounts for a growing share of electricity generation in the Philippines and Indonesia, which are failing to ramp up renewables fast enough, a new report has warned.

The growing reliance on coal in Indonesia comes despite a $20 billion international deal intended to help Jakarta wean itself off the fossil fuel.

Coal is a key source of climate-warming carbon emissions, and many major economies have pledged to move away from the fuel.

But in 2023, the share of electricity generated from coal in Indonesia increased marginally to reach a new record high of 61.8 percent, according to Ember, a London-based climate and energy think-tank.

Coal use in the Philippines meanwhile jumped nearly three percent to 61.9 percent, the think-tank said Monday.

Indonesia is the world's fourth-most populous nation and Southeast Asia's largest economy.

The increase comes with coal being used to meet rising demand in both countries, though in the Philippines, coal generation grew by more than the rise in demand.

That was because it was also used to meet a drop in production from other sources, including bioenergy and gas, Ember said.

Both countries are falling behind their regional counterparts when it comes to wind and solar energy, the group said.

Regionally, the two renewables account for an average of 4.4 percent of electricity generation, but just 3.2 percent in the Philippines and 0.3 percent in Indonesia.

And while Indonesia generates renewable energy from hydropower, that fell 10 percent last year, possibly because of drought conditions.

"Overall, Indonesia and the Philippines are the two most coal dependent countries in Southeast Asia and their reliance on coal is growing fast," the group warned.

Last year, Indonesia also became the world's fifth-largest coal power generator, overtaking South Korea for the first time, Ember said.

The Philippines aims for renewable energy to make up 35 percent of its power generation by 2030, while Indonesia is committed to reaching 44 percent the same year.

The International Energy Agency says that to reach net zero by mid-century, all coal generation that does not capture emissions must end by 2040.