Hundreds of Indonesian ground fires which sent a choking haze over parts of Malaysia and Thailand this month were lit by companies which had been charged with lighting fires in 2003, said WWF in a statement today.

The Indonesian arm of the global conservation group said that in the month to Aug 16, some 609 hotspots out of 5,420 recorded by satellite data were caused by repeat offenders who should be prosecuted by the government.

"Repeated incidents of forest and land fires, both in companies' concessions and communities' plantations, indicate public and corporate ignorance in respecting the zero burning policy" set in 2001, said WWF's Fitrian Ardiansyah.

About half of the hot spots were located in company concessions and half in community plantations, it said.

The group also called on the government to stop issuing concession licenses on peat soil areas, which burn easily and produce more haze compared to other areas. Peat areas in Riau are the main habitat of the endangered Sumatran tiger, it warned.

Fitrian told AFP the companies had been charged in court but found not guilty in 2003, the last time there was a significant haze problem.

"Local governments found that they had triggered fires to burn land. (But) when the cases were brought to the court, the court didn't find them guilty for a lot of reasons, including lack of capacity of the court to find out what had happened," he said.

Tougher action needed

Indonesia said on Sunday that some 1,200 firefighters plus teams from countries including Malaysia had extinguished all the fires on Sumatra blamed for causing the hazardous haze.

Malaysia and Singapore have both called for a more coordinated response from Asean on the annual haze problem, which in 1997-98 cost the region some 9.0 billion dollars by disrupting air travel and other business activities.

Association of Southeast Asian Nations (Asean) officials who discussed the issue last week said they would welcome help from China, Japan and South Korea to combat the recurrent crisis. They also pressed for tough action against those responsible for lighting the fires.

Malaysia, Singapore and Australia have all offered assistance ranging from firefighting to cloud-seeding to induce rain.