At least 11 people are dead and 35 more are missing after heavy rains caused a landslide near an illegal gold mine on Indonesia's central island of Sulawesi, an official said Monday.

Unlicensed mines are common across the mineral-rich Southeast Asian archipelago, where abandoned sites attract locals who hunt for leftover gold ore without proper safety equipment.

The landslide hit a remote village in the Bone Bolango District of Gorontalo Province late Saturday after spells of torrential rain, killing at least 11 and leaving more than two dozen still unaccounted for.

"Ten people died. Those who survived increased significantly from five to 20 people," said local search and rescue agency head Heriyanto, who goes by one name.

He added that another person who died had yet to be evacuated from the site of the disaster -- and so was not included in the death toll -- and that 35 people were still missing.

The number of missing had risen because more families had reported their relatives as unaccounted for, Heriyanto said.

Some victims were miners while others were people who operated stalls near the mine.

"There are also those who opened kiosks there. Not all were local residents," the rescue official said.

Several bridges to the area collapsed and rescuers were having to travel to the site of the disaster by foot due to the difficult terrain, he said.

At least 180 people had been deployed as part of the rescue operation, including police officers and soldiers, he added.

Indonesia is prone to landslides during the rainy season between November and April, but July is usually dry season and heavy rains are rare.

In May, at least 15 people died after landslides and flooding in South Sulawesi Province swept away dozens of houses and damaged roads.

A landslide in the same province the month before killed 20 people.