The firefighters were sent under a plan drawn up after health-threatening smoke from Indonesian fires blanketed large swathes of southeast Asia in 1997, the Association of South East Asian Nations (ASEAN) said in a statement.
The ASEAN statement gave no further detail of the action being taken while the United Nations Environment Program (UNEP) expressed concern the fires may cause a repeat of a haze which smothered parts of the region in 1997 and 1998 causing widespread health problems and scaring off tourists.
The fires, which started in the province of Riau on Sumatra with the onset of the dry season, have spread to southern parts of the huge island, said an official with the Indonesian government's Forest Fire Prevention and Control Project, Ifran Destianto Imanda.
''South Sumatra and Jambi should be on alert now as firespots are appearing on our monitors,'' he told Reuters.
Sumatra lies west of Singapore and Malaysia.
Many of the fires are illegally set and officials and environmental groups accuse palm oil plantation companies of lighting them to clear land.
Indonesia said Thursday it would name and revoke the licenses of companies guilty of lighting fires.
The UNEP's Asia Pacific Director, Nirmal Andrews, told Reuters in Bangkok he welcomed the Indonesian response, saying it could avert another regional haze crisis.
''The Indonesian government's intention to summon logging and plantation company owners and to review their licenses is the kind of tough measure needed to pre-empt another crisis,'' he said. ''These are early hotspots and strong steps can help check the problem.''
Andrews said about 1,200 fires had been detected on Sumatra and Kalimantan, the Indonesia part of Borneo island, earlier this week with pollution readings over the 300 level on the Pollution Standard Index (PSI), a level considered hazardous to health.
An early warning system, supported by UNEP and other regional agencies and governments, uses high-resolution satellite imagery to detect specific land holdings where there are hot spots, enabling the quick and coordinated mobilization of fire-fighting teams.
Rains have eased the fire problem in Riau, but Imanda said local residents should not become complacent.
Indonesia's environmental watchdog, Bapedal, said it had evidence a Malaysian company had set fires to clear land in Riau.
''But they may say that it was the fault of the land-clearing firm that they hire and come up with a contract that forbids the usage of fire,'' he said.
Singapore's air condition worsened to the most polluted levels of the year late Wednesday when its PSI stood at 65. An air-quality reading of 0-50 is considered good, 51-100 moderate and 101-200 unhealthy.
Environmentalists in Malaysia expect the country to feel the effects of the haze if the fires persist.
- Reuters - Thomson Reuters Foundation
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