Rights groups raised concerns over conditions at the mine, which supplies about 15 percent of the world’s coltan used in advanced electronics.

More than 200 people have been reported killed in a collapse at the Rubaya coltan mine in eastern Democratic Republic of the Congo (DRC), Lumumba Kambere Muyisa, spokesperson for the rebel-appointed governor of the province where the mine is located, told the Reuters news agency.

The mine, located some 60km (37 miles) northwest of Goma city, the provincial capital of North Kivu province, collapsed on Wednesday, and the precise number of casualties was still unclear as of Friday evening, Reuters reports.

“More than 200 people were victims of this landslide, including miners, children and market women. Some people were rescued just in time and have serious injuries,” Muyisa told Reuters, adding that about 20 injured people were being treated in health facilities.

“We are in the rainy season. The ground is fragile. It was the ground that gave way while the victims were in the hole,” he said.

Eraston Bahati Musanga, the governor of North Kivu province appointed by the M23 rebel group, told the AFP news agency on Friday that “some bodies have been recovered”, without giving a specific figure of the number of those killed and injured, but suggesting a potentially high death toll.

An adviser to the provincial governor put the death toll at more than 200, speaking on condition of anonymity to Reuters because he was not authorised to brief the media.

AFP said it was unable to confirm the death toll with independent sources as of Friday evening.

Franck Bolingo, an artisanal miner interviewed at Rubaya by AFP, said people are believed to still be trapped inside the mine.

“It rained, then the landslide happened and swept people away. Some were buried alive, and others are still trapped in the shafts,” Bolingo said.

Rubaya produces about 15 percent of the world’s coltan, which is processed into tantalum, a heat-resistant metal that is in high demand by makers of mobile phones, computers, aerospace components and gas turbines.

The mine, where locals dig manually for a few dollars per day, has been under the control of the Rwanda-backed M23 rebel group since 2024, after previously changing hands between the DRC government and rebel groups.

The heavily-armed M23 rebels, whose stated aim is to overthrow the DRC government in the capital Kinshasa, captured even more mineral-rich territory in the east of the country during a lightning advance last year.

The United Nations has accused M23 rebels of plundering Rubaya’s resources to help fund their rebellion, backed by Rwanda, an allegation that the government in Kigali denies.

Despite the DRC’s exceptional mineral wealth, more than 70 percent of Congolese live on less than $2.15 a day.