A new study into last year's Indonesian forest fires and the resulting haze over Southeast Asia says the disaster caused damage costing four-and-a-half-billion dollars.

The study -- by the World-Wide Fund for Nature and the Singapore-based Economy and Environment Programme for South-East Asia -- compiled direct losses sustained by the timber industry and agriculture, alongside the impact of air pollution on the region's public health and tourism.

The report has already been presented to the Indonesian authorities.

It recommends action to reverse policies which it says have encouraged indiscriminate land clearance by those guilty of starting the fires: mainly oil palm and timber plantations, along with subsistence farmers.