(Adds presidential spokesman, Muslim prayers)

By Ed Davies

JAKARTA, Oct 8 (Reuters) - Forest fires were still raging across Indonesia on Sunday, with visibility cut to as low as 30 metres (100 ft) in parts of Borneo island, forcing cars to use headlights and throwing air travel into chaos.

The fires concentrated on the islands of Borneo and Sumatra are a regular occurence in the dry season but appear to have worsened this year with more fires on highly flammable peatland and amid a hot spell ahead of the start of rains due this month.

Thick haze blowing across from Sumatra prompted Singapore to post a health advisory on Saturday, warning people to scale back vigorous outdoor activity.

The situation was slightly better on Sunday, with Singapore's three-hour average Pollutant Standards Index (PSI) down as low as 27, after hitting a nine-year high of 150 on Saturday, the National Environment Agency's Web site (www.nea.gov.sg) showed.

A spokeswoman at the agency said that south-southeasterly winds had blown some of the haze away from Singapore, but warned that it could only be a temporary shift.

"We expect that later in the afternoon it could shift in a south-southwesterly direction again," she said.

In the town of Palangkaraya in Indonesia's Central Kalimantan province on Borneo, visibility fell as low as 30-50 metres, according to El Shinta radio.

Cars used headlights to avoid accidents, while flights were delayed by four-five hours at the town's airport of Cilik Riwut.

The Antara state news agency said the air pollution index in the town was at the "dangerous" level and people were having to wear protective face masks even in their homes.

Fires were also still raging in the Sebangau National Park in the province.

INDONESIAN TASK FORCE

A task force of Indonesian officials arrived in Kalimantan on Sunday to assess the situation.

Purwasto, head of forest fire control at Indonesia's environment ministry, told Reuters en route to Palangkaraya that the team would look at the situation for one or two days.

In Sumatra, haze stopped boats carrying food staples to remote parts of the province from navigating the Musi river, with visibility cut to 200 metres, Metro TV reported.

Thousands of Muslims gathered in an open field on Bangka island, off Sumatra, to pray for rain, Antara reported.

This year's haze has rekindled memories of the smog that choked large areas of Southeast Asia in 1997-98, making many sick and costing local economies billions of dollars. The fires over that period were estimated to have destroyed five million hectares (12 million acres) -- an area equivalent to Costa Rica.

In Malaysia, several areas in southern Johor state near Singapore were still recording unhealthy pollution levels on Sunday, while the situation in other areas was better.

Thailand also reported light smoke in southern parts of the country and the governnment-run Thai News Agency said masks were given to people in Satun province.

FRUSTRATED NEIGHBOURS

Malaysian Plantation Industries and Commodities' Minister Peter Chin said the government would not protect any local plantation firms involved in open burning in Indonesia.

Timber and oil palm plantation companies are accused of lighting fires to clear land for planting.

Farmers, too, use slash-and-burn methods, a traditional practice magnified by a growing population, demand for land and vast areas of forest that have been cleared in recent decades.

It is illegal to carry out slash-and-burn land clearing in Indonesia, but prosecutions take time and few have stuck.

Indonesian presidential spokesman, Andi Malarangeng, told Antara the country had taken the right steps to quell the fires, but said it was tough to contain fires in remote areas and it would welcome cooperation with neighbouring countries.

Indonesia's neighbours have been sounding increasingly frustrated over a situation that Jakarta has long vowed to fix.

Singapore's Senior Minister Goh Chok Tong was quoted as saying by Channel News Asia that the island state would register its concerns with Indonesia's foreign ministry.

"I just hope that next year, the Indonesians will understand our concerns and do something about the haze, or do something about the fire before it is started by farmers and plantation owners", Goh said. (Additional reporting by Ade Mardiyati in JAKARTA, Mia Shanley in SINGAPORE, Syed Azmin in KUALA LUMPUR and Orathai Sriring in BANGKOK)

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