Louise Williams, Jakarta – Hot, dry winds across Indonesia have caused a dramatic fourfold increase in forest fires and new smog warnings, after last week's light rains and initial successes in fighting the fires on the ground.

The Ministry of Environment said yesterday that the number of major fires had increased from about 16 to 62 since Friday night, prompting renewed smog warnings in Singapore.

Changing wind patterns have produced strong, hot and dry westerlies which are pushing smoke from fires in Sulawesi into Kalimantan, and smoke from Kalimantan into Sumatra, Singapore and southern Malaysia.

The Singapore Government issued a new smog warning at the weekend as air pollution levels rose above the safe limit.

The Ministry of Environment said the most seriously affected areas were central and west Kalimantan where airports remained closed and dozens of major fires were burning. In central Kalimantan, large tracts of peat are on fire and cannot be easily extinguished even with heavy rain.

Last week, residents of many areas which have suffered the choking smoke haze for two months celebrated rain, but the falls were patchy and light and meteorologists warned that the monsoons would be delayed, probably until next month.

In Sumatra, where Australian water bombers are tackling fires in the far south, two new blazes were reported in Lampung and 21 in South Sumatra. Thick smoke and visibility as low as 10 metres means the planes cannot operate in South Sumatra.

An environmental expert in Kalimantan said the damage to the rainforest would take at least 25 years to repair and predicted devastating floods would accompany the rain.