Indonesian police arrested seven corporate executives on Wednesday in connection with illegal forest fires across Sumatra and Kalimantan, as part of a wide-ranging effort to stop the haze crisis.

Suspects included a senior executive from Bumi Mekar Hijau, a unit of Singapore-based Asia Pulp and Paper (APP), which is also Indonesia’s largest pulp and paper producer.

The national impetus includes deploying more police to help with firefighting and handling probes against culprits, and increasing cloud-seeding sorties to douse the blazes, especially those burning on dry peatlands.

These carbon-rich peatlands produce the thick haze that has blanketed many parts of Indonesia, as well as neighbours Malaysia and Singapore in recent weeks, bringing the air quality down to unhealthy and sometimes hazardous levels.

The government’s pledge to step up enforcement and expand cloud-seeding operations, as air pollutant levels improved owing to the rain yesterday, raises hope among millions affected by the haze.

Several parts of Sumatra and Kalimantan have been ravaged by forest fires in recent weeks because of the dry season, which was exacerbated by the El Niño effect.

A weather phenomenon, El Niño, reduces rainfall in south-east Asia, resulting in hot and dry weather, which causes forests to burn more easily. But Indonesia’s national disaster management agency (BNPB) said sporadic rain in recent days may offer respite while the presence of clouds facilitates cloud-seeding.

“We understand the El Niño will last until late November, but a weather anomaly has developed – we had rain north of the equator line,” said BNPB chief Willem Rampangilei.

Rampangilei was speaking to The Straits Times on Wednesday after a meeting on the forest fire and haze crisis with president Joko Widodo.

“Cloud-seeding is not effective if there are no clouds at all, but we expect the clouds to increase in the coming days,” he added.

The Indonesian national police chief Badrodin Haiti told reporters yesterday that he has deployed 682 officers, including 68 investigators, to affected areas in Sumatra and Kalimantan, to reinforce firefighters and soldiers already on the ground.

Students ride on a boat as they go to school while haze from wildfires blanket the Musi River in Palembang, South Sumatra, Indonesia, 17 September. Photograph: Tatan Syuflana/AP

The Straits Times understands that the national police have identified firms such as plantation company Bumi Mekar Hijau for suspected environmental crimes.

A senior executive from the South Sumatra-based firm, identified by his initials JLT, was arrested on Wednesday morning and is currently being interrogated.

An APP spokesman, responding to queries from The Straits Times, said last night it was “not aware of any new formal police charges against any of our suppliers at this time”. She maintained that APP has operated a “zero burning” policy in its supply chain since 1996.

Senior members from six other companies accused of similar offences were also picked up on Wednesday for questioning, General Badrodin added. Bumi Mekar Hijau, which has pulpwood concessions in Ogan Komering Ilir in South Sumatra, is still facing trial for a separate civil case in the Palembang.

The environment and forestry ministry had previously demanded that Bumi Mekar Hijau pay 7.8tn rupiah (S$780 million) to the state for damages from burning land. If found guilty again this time, the company’s management could be jailed for up to 10 years.

This year, provincial police units in the six areas affected by the haze have been investigating 24 companies and 126 individuals for breaching environmental laws.

According to figures from environment and forestry minister Siti Nurbaya Bakar, estimates show 52,000 hectares of land in Sumatra were ravaged by fire, while 138,000 hectares in Kalimantan were scorched. However, the number of hot spots recorded thus far this year remains fewer than that recorded last year, said the BNPB.