Killer haze from forest fires that raged across Indonesia last year may have caused more than 100,000 premature deaths in Indonesia, Singapore and Malaysia, according to a new report that suggests a drastically higher death toll than Indonesian government figures.

Harvard and Columbia University researchers used air pollution readings to calculate exposure to the deadly smoke.

Indonesians were the worst affected with an estimated 91,600 excess deaths, the report found. Credit:Getty Images

"We estimate that haze in 2015 resulted in 100,300 excess deaths across Indonesia, Malaysia and Singapore," says the report, which was published in Environmental Research Letters journal on September 19.

It says this is more than double the estimated number of deaths as a result of haze in 2006, with much of the increase due to fires in Indonesia's South Sumatra province.