Two Australians rescued after helicopter crashes into Borneo river

Two Australians have survived a helicopter crash after it nosedived into an Indonesian river while fighting fires on the island of Borneo.

Video shows the helicopter collecting water for water-bombing operations from a river in Indonesia's South Kalimantan province.

The aircraft then loses control, losing altitude and crashing into the river.

Indonesia's National Disaster Mitigation Agency (BNPB) said two Australians survived and the cause was being investigated.

An Indonesian crew member is missing.

Video shows local residents helping to pull the wreckage out of the river.

The two Australian men are receiving medical attention while personnel from Indonesia's search and rescue agency, Basarnas, are heading to the scene.

The helicopter was contracted by Indonesian authorities as the country faces its worst forest and land fire season in more than a decade.

"In Indonesia, the helicopter frequently supports various disaster response missions of the National Disaster Management Agency, with flight routes covering Banjarmasin, Pontianak, and Surabaya," BNPB spokesperson Berton SP Panjaitan said.

"The relevant team is currently on stand-by in the field, and a complete report detailing the chronology and exact cause of the accident is being compiled for immediate release to the public and authorities."

Flight tracking data shows the helicopter leaving Banjarmasin, the capital of South Kalimantan this morning and heading to fire-affected areas before the crash.

The crash comes after three Indonesian crew were killed after a separate water-bombing helicopter crashed earlier this week in Central Kalimantan.

The helicopter was carrying eight crew and also crashed while loading water.

Intense forest and land fires have been burning across large swathes of Indonesia, particularly in the Indonesian portion of Borneo, known as Kalimantan, in Sumatra and in Papua.

The fires often burn on peatland, which can be notoriously difficult to put out as embers can burn far below the ground.

Environmental monitor Nusantara Atlas said satellite monitoring data shows more than 1.9 million hectares have burned across Indonesia up to September this year.

The country's environment minister said more than 100,000 personnel have been involved in fighting fires across the country.

The fires have spewed a toxic smoke haze across parts of the region and in Indonesia alone more than 400,000 cases of acute respiratory infections have been recorded according to the country's health ministry.

The country has a fire season annually, but this year has been supercharged by drought and heat caused by a Super El Niño.

The fires are commonly linked to land clearing operations, particularly to clear land for plantations.

Indonesian police have named more than 240 people and 20 companies as suspects, accused of deliberately or negligently lighting fires.