Indonesia's disaster agency says deliberately set fires are burning through peatland forests in the province of Riau, just two days after President Joko Widodo incorrectly claimed there'd been no fires for several years.

The disaster agency said Tuesday that 843 hectares of land have burned in Riau since the beginning of the year and that fire-fighting teams are currently battling blazes in several locations.

Widodo has had to correct claims made in a presidential election debate on Sunday.

Local media reported he now says the amount of land affected has fallen dramatically since disastrous fires in 2015 when 2.6 million hectares (10,000 square miles) burned, polluting Indonesia and neighboring countries with a health-damaging haze.

Ministry of Environment data shows more than 510,000 hectares of land burned last year.