The fires, covering millions of acres, have been burning for weeks, triggering fears of a repeat of the months of choking haze in 1997 that cost the region billions in economic losses.
Neighbouring nations have called on Indonesia to ratify swiftly a regional treaty to fight the fires, and warned that they will delay financial assistance if it does not.
In Sumatra's Jambi province yesterday, smoke from more than 100 fires reduced visibility to less than 50 yards.
In Riau province, Sumatran elephants may be moved out of a national park after uncontrolled fires destroyed 247 acres.
Saut Manalu, a senior official at the Tanjung Puting national park on Borneo, where 6,000 orang-utans live, blamed deer hunters for setting many of the fires, which he said were further endangering the under-threat species.
"We can hear them scream at night," he said. "We are focusing on how to put out the fires. If they go out of control, we will take care of the animals. We may need to evacuate them.
"In order to lure deer, hunters often set ablaze certain areas so that fresh grass could grow on the burnt land. Deer would graze there because they like young leaves."
Indonesia's neighbours are increasingly frustrated at Jakarta's failure to tackle the annual dry-season fires.
Singapore, which has suffered from the haze since the start of October, saw its air Pollutants Standards Index climb to an unhealthy 130 yesterday. Malaysia's foreign minister said a collective fund was needed to battle the problem.
"We need to have a fund where everybody contributes, because we are all affected," he said.
"I don't think it will be fair for any country like Malaysia [to] spend on our own. It's too big, it's too much. The source is in Indonesia."
Local officials praised the steps taken by environmental ministers from Thailand, Malaysia, Brunei and Singapore to pressure Indonesia to ratify the haze agreement, but a leading local environmental organisation said it failed to adopt adequate preventive measures.
"It failed to come up with a concrete agenda both in the short and long term," said Chalid Muhammad, executive director of the Indonesian Environmental Forum.
Indonesia should have proposed emergency laws to empower the government to revoke permits from plantation companies found to be using illegal cut-and-burn methods, he said.
Malam Sambat Kaban, Indonesia's forestry minister, said more than 75 per cent of the fires were not in government forests, but on plantations and farms of private companies and local people.
He said the Central Kalimantan area was the worst hit, with about 2.5 million acres of peatland in one area on fire. Peat fires are difficult to extinguish and can burn for months.
Indonesia bans slash-and-burn practices by farmers and plantations, but prosecutions take time and few have stuck.
ACHMAD SUKARSONO AND ZAKKI HAKIM