Kuala Lumpur – Forest fires in Indonesia's Sumatra province covered Kuala Lumpur and 32 other areas of Malaysia with a smoky haze Tuesday, reducing visibility in some places to a half-mile.

In Kuala Lumpur, Malaysia's biggest city and financial capital, traffic slowed to a crawl and the acrid smell of burning vegetation filled the air.

The Department of Environment said air quality in an area in central Perak state was unhealthy, and it downgraded air quality in 32 other areas – including Kuala Lumpur – from good to moderate.

It said satellite images showed 587 "hot spots," or fires, in Riau and northern Sumatra in Indonesia. The province is separated from peninsular Malaysia by the Malacca Strait. Seventeen hot spots also were reported in Malaysia's Sarawak state, and 16 in Indonesia's Kalimantan province, both on Borneo island.

The weather bureau said hazy conditions would persist for up to two days – so long as winds were blowing from Sumatra to Malaysia.

Forest fires often break out in the region during dry spells because of the spread of illegal land-clearing fires or carelessly discarded cigarettes.

Kuala Lumpur last reported unhealthy air quality levels in 1997, when brush fires in Indonesia destroyed some 25 million acres of vegetation, cloaking much of Southeast Asia with haze. Economic losses from those fires topped $9.3 billion.