JAKARTA - The Indonesian government on Saturday (Sept 14) vowed to pursue criminal charges against companies involved in open burning as it sealed off more plantations amid worsening haze in the region.

The authorities had sealed off plantations operated by 42 companies whose concessions were affected by fires, said the Environment and Forestry Ministry. The area sealed off covers more than 6,000ha.

A company could see its executives sent to prison under the criminal law, the Environment and Forestry Ministry's director-general for law enforcement Rasio Ridho Sani told a press conference on Saturday. He said the company could also be fined or have its profits seized.

"The government has a serious commitment to prosecute (these companies). We will be able to address the fires only if we can change the behaviour of the people and companies, and we will take strict measures to do that," he said.

Mr Rasio pushed for offenders to be brought to book, pointing to the experience of the previous bout of severe haze in 2015.

He said official data showed that hot spots had dropped sharply in the past few years in areas where companies which caused fires in 2015 were punished severely.

That year, Indonesia was covered with choking haze which also blanketed neighbouring Singapore, Malaysia and Thailand, for over a month. South-east Asia's largest economy suffered from around US$16.1 billion (S$22.1 billion) in losses because of the massive fires, said the National Disaster Management Agency (BNPB).

Apart from levying criminal charges, the government would be taking other steps against errant companies, said Mr Rasio. He said not only would their operational permits be revoked, they would also have to pay compensation for the burning and restoration of ravaged areas.

The authorities have identified four companies as suspects and are in the process of identifying individuals responsible for the fires, Mr Rasio said.

Investigations would also be carried out against the companies whose plantations were sealed off, he added.

They include subsidiaries of four Malaysian groups - Sime Darby, IOI Corporation, Kuala Lumpur Kepong Berhad (KLK) and TDM Berhad - and an Indonesian company owned by a Singapore-based group - Sampoerna Agri Resources Pte Ltd.

Home to the world's third-largest tropical rainforest, Indonesia is struggling to curb fires on Sumatra and Kalimantan as it faces a longer-than-usual dry season this year.

From January to August, fire has engulfed 328,724ha, 27.3 per cent of which were highly combustible peatlands , BNPB figures showed. The agency has deployed 9,072 personnel to fight the fires and mobilised 42 helicopters for water-bombing missions.

The emergency response team has also conducted cloud seeding to produce rain, with the latest operation conducted over Riau province in Sumatra.

At the same press conference on Saturday, BNPB chief Doni Monardo called on regional officials to do more to tackle the fires, saying that he has received complaints from police officers and military personnel about their lack of responses in addressing the issue in their territories.