Indonesia said Wednesday it hopes to ratify a regional treaty by early next year to fight smog from forest fires that bring misery to millions, but green activists poured cold water on the deal.

"We hope we can ratify the agreement by the end of the year or early next year," the country's Environment Minister Balthasar Kambuaya told reporters.

Earlier Wednesday Kambuaya and environment ministers from four other ASEAN countries, which together form the Southeast Asian bloc's "haze committee", met to discuss ways to prevent the Indonesian forest fires.

The blazes on Sumatra island, caused by the slash and burn farming method of land clearance for cultivation, in June left neighbouring Singapore and Malaysia choking on the worst haze in more than a decade.

The air pollution scared off tourists, forced schools to close and caused a rise in respiratory illnesses.

Indonesia is the only member of the Association of Southeast Asian Nations which has still not ratified the bloc's Agreement on Transboundary Haze Pollution, brokered in 2002.

The treaty aims to stop cross-border smog from forest fires by requiring parties to prevent burning, monitor prevention efforts, exchange information and provide mutual help.

It also binds signatories to "respond promptly" to requests for information from countries affected by the smoke, and to take steps to implement their obligations under the treaty.

T. Jayabalan, a public health consultant and advisor to Friends of the Earth Malaysia, lauded Jakarta's move to vow to ratify the treaty but warned that lax law enforcement would mean that the smog problem would not go away.

"It is a lukewarm measure. You can have all the regulations, but if enforcement is lax, we will continue to have haze," he told AFP.

Jayabalan said large swaths of combustible peatland in Sumatra also meant enforcement would be difficult.

"What we need is meaningful self-regulation. Public health should override profits," he said. "We need a code of practise, which includes deterrent measures to prevent burning where directors of companies are liable to be jailed."

Indonesia, a freewheeling democracy since the fall of strongman Suharto in 1998, has blamed its parliament for the long delay in ratifying the haze agreement.

Jakarta had sought legislators' approval for ratification, but the proposal was rejected in 2008.

The pact has again been submitted to the legislature.

Faizal Parish, senior technical advisor to ASEAN's peatland forests project, said there was no quick fix to the dreaded haze.

"There is no magic wand. The root causes are there. There will be some people who will do some land clearing by fire," he told reporters on the sidelines of the gathering.

"It is going to take a long time to reverse the situation," he said, adding that with dry weather expected there could be more haze in the coming months.

Kambuaya said eight companies are being probed in connection with the recent haze crisis and the government would announce their identities "as soon as possible".

He said Jakarta was prepared to share concession maps of fire-prone areas with other governments, but said they would not be made available to the public as Singapore had requested.

The concession maps show who has the right to plant crops or log particular tracts of land, allowing them to be investigated and prosecuted for fires.

"We are not allowed to publish concession maps to the public," he said.

The Sumatra fires have been largely blamed on palm oil firms using the illegal but cheap method of burning vast tracts of rainforest and peatlands to clear them for planting.

Indonesia is the world's top producer of palm oil, which is used for many everyday items ranging from soap to biscuits.