Indonesian officials said on Wednesday dozens of rescuers were using spades and ropes to dig out around 45 people who were feared buried by the collapse of an illegal gold mine on the island of Sulawesi that killed at least one person.

Rescuers said they could hear the voices of some of those trapped in makeshift mining shafts in a muddy hillside in the Bolaang Mongondow area of North Sulawesi province and believed many were still alive.

"We are able to detect that many of them are still alive because we can hear their voices, as there are some places where the air is getting in and out and there are gaps in the mud," Abdul Muin Paputungan of Indonesia's disaster agency said.

Indonesia's disaster mitigation agency said one body had been recovered by 8 am on Wednesday (0100 GMT) after the mine collapsed the previous evening. Indonesian media reports put the death toll at three.

At least three bodies had been found and 15 people rescued by 8 am on Wednesday (0100 GMT) after the mine collapsed the previous evening, according to the disaster mitigation agency and media reports.

"When dozens of people were mining for gold at the location, suddenly beams and supporting boards they used broke due to unstable land and numerous mining shafts," disaster agency spokesman Sutopo Purwo Nugroho said.

Photos released by the agency showed rescue workers and villagers on a muddy hillside at night scrambling to pull out survivors and carry them away on stretchers.

Sugiharto estimated that an experienced miner might be able to survive for up to three or four days under the rubble if they could find air pockets and were not crushed by rocks.

"They can breathe slowly and usually they don't panic. If there is no poisonous gas they can survive for some time," he said.

The Indonesian government has banned such small-scale gold mining, although regional authorities often turn a blind eye to the practice in more remote areas. With little regulation, such mines are prone to accidents.