The haze from Indonesian forest fires began to clear in Thailand's deep south but worsened today on the popular resort island of Phuket, pollution officials said.

Smoke and dust was being blown over Malaysia and into Thailand from peat fires raging on Kalimantan on the Indonesian side of Borneo island, more than 1,000 kilometres southeast of Thailand's eight southern provinces that have been affected.

Thai officials said the air pollution index had risen steadily on Phuket, the jewel in the crown of Thailand's tropical tourism industry, and warned of a possible return of haze to the deep south in coming days.

"The haze (level) in southern provinces today is safe, but Thailand risks being affected by haze in one or two days, and the pollution control department will closely monitor the situation," it said in a statement.

"The average is still below the standard hazardous measure of 120 micrograms per cubic meter," the department added.

Measurements of 42.2 micrograms were recorded in the southern economic hub of Haadyai, down from 66.9 yesterday.

But Phuket, which is on Thailand's southwestern Andaman coast, registered 56.8 yesterday before seeing its reading jump to 83.3 this afternoon, an official at the department said.

155,000 masks distributed

Kitti Phatanachinda, vice-president of the Phuket Tourism Association, said the haze was unlikely to affect tourism on the island, which is suffering from the effects of last December's killer tsunami.

"The haze is foggy here, but it's not that bad," Kitti told AFP, adding that local meteorologists were calling for rain which could clear away the haze.

"We're not too worried, it shouldn't get worse than this."

Vichien Kaenploy, chief health officer of Songkhla province, said the haze had yet to present significant health risks.

"The air is much better now and so far we have no reports of irregular increases in the number of (respiratory) patients, but we have handed out thousands of masks to the public," he said.

The health ministry has sent 155,000 masks to southern provinces.

Haze is a recurring problem in Southeast Asia, and the worst-ever bout, in 1997 and 1998, cost the region an estimated US$9 billion in damages by disrupting air travel and other business activities.