Indonesia's disaster chief on Thursday defended the country's efforts to fight forest fires that have blanketed Southeast Asia in choking haze, and said he believed rains would arrive within a month to finally douse the blazes.

"Are we able to manage the fires? The answer is clearly a yes... we are not overwhelmed, we can manage it and there is progress," National Disaster Management Agency chief Willem Rampangilei told reporters.

Malaysia, Singapore and large expanses of Indonesia have suffered for weeks from acrid smoke billowing from fires on plantations and peatlands that are being illegally cleared by burning.

Singapore has offered to help in fighting the fires but Rampangilei said it was not needed.

"Indonesia welcomes the offer but at this moment, everything is under control," he said.

"We can see some achievements, some progress that we have successfully extinguished a number of fires," he added.

More than 20,000 troops, police and other personnel have been sent to Sumatra and Kalimantan to fight the fires through waterbombing and chemically inducing rainfall.

"Indonesia has tried all it could to douse the fires... and is still working very hard," he said.

Rampangilei said while the firefighters have successfully subdued the flames, the choking smog remains a problem but he is hopeful the approaching rainy season will put an end to the crisis.

"We need heavy rainfall or sufficient waterbombing so, it takes time to resolve the haze," he said.

"I hope the haze will be resolved in a month, that is either end October or early November," he said.

Indonesia has faced pressure from its neighbours to address the problem since it first emerged nearly 20 years ago.

Singapore officials have reacted with outrage to Indonesian Vice-President Jusuf Kalla's comments that the country's neighbours should be grateful for good air quality most of the year, and that Jakarta need not apologise for the crisis.