JAKARTA, Indonesia (AP) — Indonesia intensified its ground and aerial firefighting operations Monday as huge blazes in central and western regions scorched wide areas of forests and peatland, creating a choking haze that blanketed cities and crossed borders.

Indonesian police have arrested 72 people suspected of starting some of the forest and peatland fires, while four companies are under investigation for allegedly using fire to clear land at low cost.

Emergency services have been battling fires driven by an intensifying El Nino pattern and a prolonged dry season, generating dense smoke that crossed into Malaysia and Brunei, according to the National Disaster Management Agency, or BNPB.

Fires remained active in several regions on Monday, according to the agency, while large-scale suppression efforts continue in fire-prone provinces including West, Central and South Kalimantan on Borneo island and in Riau, South Sumatra and Jambi on Sumatra island. The fires are part of a broader surge in wildfire activity across Indonesia this year.

Drought, strong winds and dry vegetation have complicated efforts to contain the fires, the BNPB said in a statement. Some hot spots remained inaccessible to more than 24,000 ground firefighters who were deployed on Sumatra and Borneo, prompting local officials to request additional water-bombing support.

After visiting areas devastated by forest and peatland fires in Central Kalimantan on Saturday, President Prabowo Subianto traveled to fire-affected Riau and its neighboring province of South Sumatra on Monday, where more than 36,000 hectares (89,000 acres) have burned in 10 provinces, to encourage authorities to get the haze cloud under control.

Prabowo vowed the government would continue supporting firefighting operations, including through the deployment of additional water-bombing helicopters and oxygen supplies for firefighters. He urged the authorities to “thoroughly document and report the work being carried out by firefighting teams” directly to him.

Prabowo also called for stronger public education and outreach efforts, saying the central government will deploy about 1,000 military and police officers to work alongside regional authorities in raising awareness and preventing forest and land fires.

The latest satellite data from the Environment Ministry showed South Sumatra recorded the highest number of hot spots nationwide with 1,429, followed by West Kalimantan with 1,226 and Central Kalimantan with 811. East Kalimantan logged 576 hot spots, ahead of Riau with 503, while West Papua and Jambi recorded 468 and 458 hot spots, respectively.

Forestry Ministry data indicated that nearly 94,000 hectares (232,000 acres) were burned in July alone.

The Transportation Ministry said it has authorized the use of 35 foreign-registered aircraft to support wildfire response operations, including water-bombing missions and aerial patrols. The ministry said the aircraft can be rapidly redeployed to disaster-hit areas as conditions change, while complying with Indonesian aviation safety regulations.

Indonesia is actively intensifying weather-modification operations to help firefighters combat wildfire by inducing rainfall through the dispersal of salt particles into suitable clouds, with 30 aircraft for water-bombing and cloud-seeding over Kalimantan and another 22 helicopters covering Sumatra.

Malaysia said on Monday that Indonesia has granted permission for its aircraft to enter Indonesian airspace to conduct cloud-seeding operations along their shared border as the two neighbors step up efforts to tackle the worsening haze.

Malaysia is preparing an operational plan and could also offer help to Indonesia to fight fires if requested, Environment Minister Arthur Joseph Kurup said, adding that the measures were critical to ensure air quality improves as Malaysia prepares to celebrate National Day on Aug. 31 to mark independence from British rule.

Commemorations for the annual Malaysia Day on Sept. 16 — marking the nation's unification — will be held in the eastern state of Sarawak on Borneo, one of the areas most affected by the haze, Kurup said.

Nearly 600 schools in Sarawak were closed last week as air quality deteriorated, affecting about 200,000 students, while officials expect hot and dry conditions to persist into October.

Fires are a regular problem during the dry season in Indonesia, a vast archipelago nation of more than 17,000 islands, with often strained relations with neighbors.

Plantation owners and traditional farmers often start fires to clear land for farming, triggering hazardous haze that reduces visibility, disrupts land and air transportation and threatens public health, sometimes affecting neighboring countries in Southeast Asia.