"According to the Meteorology agency, this year's dry season is very dry, not wet like last year. That's the problem," Partono said. "Looking at the fluctuation of hot spots, this year could be worse than last."

Partono said he had recorded 8,000 hot spots since January. Last year's dry season was wetter than usual, resulting in 35,000 hot spots, down from 144,000 in 2006.

In the past, Indonesia's neighbours have grown increasingly frustrated by the annual fires, most of which are deliberately lit by farmers or timber and palm oil plantation companies to clear land for cultivation.

Malaysia's Meteorological Department said worsening haze has cut visibility in the busy Malacca strait to below 5 km (three miles) and said that it could be dangerous to ships that do not have navigational aids.

A report last year by the World Bank and Britain's Department for International Development said Indonesia was among the world's top three greenhouse gas emitters because of deforestation and forest fires.

Forest and land fires account for 57 percent of Indonesia's non-industrial greenhouse gas emissions, the report said. (Reporting by Olivia Rondonuwu; Editing by Sara Webb and David Fox)