Members of Indonesian Search and Rescue (SAR) team pull out a body of a gold miner after an unlicensed gold mine collapsed at Bolaang Mongondow district of North Sulawesi province, Indonesia, Feb. 28, 2019. (Xinhua/Stringer)

JAKARTA, March 2 (Xinhua) -- The death toll from collapse of an illegal gold mine in central Indonesia has reached nine as unstable soil condition vulnerable to another mine slide hampered efforts to rescue the trapped miners, a disaster agency official said on Saturday.

Over 60 miners were working underground on Tuesday when the incident hit the unlicensed mine in Bakan village of Bolaang Mongondow district in North Sulawesi province, according to the National Disaster Management Agency.

So far, 19 miners have been rescued, most of whom sustained injuries and were receiving medical treatment at a nearby hospital, said Abdul Muin Peputungan, head of the emergency unit of the Disaster Management Agency in Bolaang Mongondow district.

At least three survivors have been shifted to a bigger hospital for their serious injuries, such as broken backbone, which require an immediate surgery.

The official revealed that the threat of further landslide aborted a plan to operate three excavators at the scene to remove the rubble and open access to the tunnel.

"Another landslide in the mine was occurring. When we were trying to enter the mine, we could hear the sounds of falling soil and rocks," he told Xinhua.

"This endangers the rescuers and the excavator could also be plunged downward or buried by the rubble should a landslide take place," he added.

However, the official said the search and rescue efforts persisted. "We set up three rescue teams working alternately every day," Abdul said.

Sutopo Purwo Nugroho, spokesman of the National Disaster Management Agency, said that poor geographical condition of the mine, which is situated in steep slopes, has also slowed the rescue operation.

Poor mine infrastructure and too many holes dug by miners amid unstable soil condition were blamed for the incident, according to the agency.

The government has prohibited operation of illegal gold mines, which are often situated in remote areas.

With lacking of safety standard, such activities have often triggered mine incidents in Indonesia, a natural resources-rich nation.