A landslide at an illegal gold mine has killed nine men in remote eastern Indonesia, an official said Friday, the latest deaths in an industry that is booming across the sprawling archipelago.

Four people were still missing and two others were rescued alive after the landslide struck Wednesday near Dageuwo village, Papua province, local search and rescue chief Marsudi told AFP.

Rescuers had to fly to the scene of the accident in the country's easternmost province, as the mountainous, remote area could not be reached by land, said the official, who like many Indonesians goes by one name.

All the victims were believed to be illegal miners, he added.

Illegal gold mining has boomed in Indonesia in recent years as the price of the precious metal has surged, and deaths are common.

But experts warn that the widespread practice of using mercury to extract gold from ore is putting the health of miners at risk and poisoning communities where they work.

The United Nations estimates that up to 15 million so-called "artisanal small-scale gold miners" operate in 70 countries worldwide.