The haze shrouding Peninsular Malaysia worsened today as smoke from fires in Indonesia drifted over the heavily populated west coast, officials said.

The Department of Environment said the air pollution index in the country's busiest port, Port Klang, climbed to 86 - close to unhealthy levels, which range between 101 and 200.

The coastal fishing town of Kuala Selangor posted a reading of 81 while in the tourist destination of Malacca, just south of the capital, the index was 80.

"The haze and the movement of smoke particles rely on wind direction," a meteorological department official told AFP.

"Right now the west coast states are recording higher levels of haze because the wind direction is from south to southwest," he said.

The official said most of the hotspots or burning zones were located in the forests in Sumatra island which is separated from Peninsular Malaysia by only a narrow waterway.

Sarawak worst affected

In Sarawak, haze persisted in the capital city of Kuching where the index edged up to 74 and 73.

Burning in Indonesia and some parts of Malaysia to clear land for crops causes an annual haze that afflicts Malaysia, Singapore and Thailand as well as Indonesia itself.

Malaysia's worst-affected region so far this year has been in Sarawak where Kuching had an unhealthily high reading of 157 last week.

Indonesia's neighbours have urged it to curb the annual haze crisis by cracking down on forest fires, warning that the choking pollution is hurting economies and deterring tourists.

"We have to contend that this is something that will happen unless real serious efforts are being put by the governments where the haze originates," Malaysia's Trade Minister Rafidah Aziz said at regional talks.

See latest haze map