Indonesia has one of the world's highest rates of deforestation, with key drivers including timber plantations, palm oil cultivation and, increasingly, the mining of critical minerals.

Its rainforests are some of the world's most biodiverse and provide critical habitats for threatened and endangered species, and are key carbon sinks.

The report from NGO Auriga Nusantara said 261,575 hectares of primary and secondary forests across Indonesia were lost in 2024, over four thousand more than the previous year.

It is the third year running that deforestation has increased, the group said, with the vast majority of losses taking place in areas opened for development by the government.

"It is worrying, as it shows the increase of legal deforestation," said Auriga Nusantara's chair Timer Manurung.

He called for "urgent" protection of forest in Kalimantan, where the highest losses were recorded as the country's new capital is built, and in Sulawesi.

The report comes as Indonesian environmentalists raise alarm over government plans to convert millions of hectares of forests for food and energy use.

President Prabowo Subianto, who assumed office in October, has pledged to boost food and energy self-sufficiency, including by expanding bio-based fuels to lower fuel imports.

Environmental groups warn the plans would spell disaster for the country's forests.

"We ask President Prabowo to issue a presidential regulation to protect all remaining natural forest," Timer told AFP.

The report is based on satellite imagery, which was analysed to confirm deforestation, and followed up with field visits to areas representing tens of thousands of hectares of forest loss, Auriga Nusantara said.

While deforestation occurred in all of Indonesia's provinces except the region around Jakarta, the biggest losses were seen in Kalimantan.

One driver in the region has been the designation of an area for the new capital, the report said.

Two regional governments in the area have proposed opening up hundreds of thousands of hectares of forest to potential development, the group warned.

Most deforestation however was driven by commodities, including timber, mining and palm oil.

Officials at Indonesia's Environment and Forestry Ministry did not immediately respond to a request for comment.

The government has previously disputed deforestation claims made by environmentalists, and said estimates overstate forest loss by miscounting changes in plantations as deforestation.

Auriga Nusantara said its count excluded loss in timber plantations and plantation forest, but does cover both primary forests and regenerated "secondary" forest.

The report also sounds the alarm on deforestation for biomass production, which has seen forest levelled to plant quick-growing species that will provide wood biomass.

Indonesia is keen to boost domestic use of biomass energy and export, particularly to Japan and South Korea.

The group said about 42 million hectares of Indonesia's natural forests are unprotected by law, including millions of hectares already inside concessions.

While the amount of forest loss has risen in recent years, it is still down sharply from a peak around 2016.