More than 200 people were killed this week in a collapse at the Rubaya coltan mine in eastern Democratic Republic of Congo, Lumumba Kambere Muyisa, spokesperson for the rebel-appointed governor of the province where the mine is located, told Reuters on Friday.

Rubaya produces around 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 site, where locals dig manually for a few dollars per day, has been under the control of the AFC/M23 rebel group since 2024.

The collapse occurred on Wednesday and the precise toll was still unclear as of Friday evening.

"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 said, 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."

An adviser to the governor said the number of confirmed dead was at least 227. He spoke on condition of anonymity because he was not authorised to brief the media.

The United Nations says AFC/M23 has plundered Rubaya's riches to help fund its insurgency, backed by the government of neighboring Rwanda, an allegation Kigali denies.

The heavily-armed rebels, whose stated aim is to overthrow the government in Kinshasa and ensure the safety of the Congolese Tutsi minority, captured even more mineral-rich territory in eastern Congo during a lightning advance last year.