Indonesian police have doubled the number of arrests this year in connection with land and forest fires to more than 450 suspects, in a move aimed at deterring recalcitrant farmers and companies from clearing land illegally by burning.

National police chief Tito Karnavian told reporters yesterday that the arrests, together with measures such as the deployment of "very effective" firefighting teams, and more favourable weather conditions, have helped to keep the number of hot spots lower this year.

Hot spots detected this year have been in the low hundreds, with the highest being 482 on Aug 16. In August last year, the number of hot spots reached 14,451.

"The number of people arrested this year has risen compared with last year," the four-star police general said. "This is one factor why the number of forest fires has fallen significantly."

In past years, the annual dry season, peaking in September, raised the number of hot spots from forest and plantation fires.

Commissioner General Ari Dono Sukmanto said yesterday that besides the 454 individuals, a number of people linked to nine companies suspected to have "started the fires" were also arrested between January and August this year.

Last year, police arrested 196 individuals and people linked to 25 errant companies, he added.

President Joko Widodo has ordered the authorities to clamp down on errant farmers and companies, while beefing up firefighting resources in high-risk areas to prevent a repeat of the haze crisis last year.

Millions of people in Indonesia and its neighbouring South-east Asian countries were affected by thick smoke from the fires that shrouded the region last year.

Earlier this week, General Tito urged regional police chiefs to get tough on individuals and companies guilty of slash-and-burn activities, a method of land clearing known to spark uncontrollable forest fires which lead to haze.

Meanwhile, Indonesia's Ambassador to Singapore, Mr I Gede Ngurah Swajaya, said the Republic has offered assistance to put out peatland and forest fires on Sumatra and Kalimantan islands. "The Singapore government has already offered to douse the fires - it has offered a plane and a helicopter," he was quoted as saying by state news agency Antara on Wednesday.

Jakarta has not decided whether it would accept the offer because the forest fires this year "are not as hazardous as last year", he added.