A labourer at the Rubaya coltan mine, which is controlled by M23 rebels, in the eastern Democratic Republic of Congo, in March, 2025.Zohra Bensemra/Reuters
A mining disaster that killed at least 200 people in eastern Congo is casting a harsh spotlight on an unregulated mineral trade whose profits are helping finance the Rwanda-backed M23 rebel militia.
The catastrophe was triggered by heavy rains and massive landslides at the Rubaya mining site, a vast collection of informal pits and shafts that provides an estimated 15 to 30 per cent of the world’s coltan supply. Coltan is processed into tantalum, a vital element in cellphones, computers and other electronic devices.
The M23 rebel group captured Rubaya in 2024 as part of a sweeping offensive across the eastern provinces of the Democratic Republic of the Congo. Since then, the militia has generated about US$800,000 monthly from taxes on the coltan trade, according to United Nations investigations.
The landslides took place last Wednesday and Thursday, but the extent of the deaths did not become public until late on Friday. Some local reports suggest that the final death toll could be 400 or more. Many bodies could still be missing: buried under rubble, trapped in underground shafts or swept downstream by rivers.
More than 200 people killed in coltan mine collapse in eastern Congo, official says
Thousands of impoverished people toil daily in the Rubaya mines, using only shovels and their hands, for a few dollars a day.
Congo’s government has long accused Rwanda of using M23 to loot the resources of the country’s east. In a statement this weekend, the government said M23 was flagrantly violating the law by pillaging the Rubaya mining pits and ramping up their production sharply over the past year.
Between 112 and 125 tonnes of coltan are extracted from Rubaya every month and transported across the border to Rwanda, in an “industrial-scale illicit supply chain” for the benefit of Rwanda, the government said. It described the mining as a war crime under international law.
The mining site has a “complete lack of safety standards” and a “recurring pattern of endangering civilian populations,” it said, citing more than 300 deaths in similar circumstances at Rubaya last year.
Because of M23’s armed occupation of Rubaya, the Rwandan government was able to increase its coltan exports by more than 200 per cent last year, the Congolese statement said. “This exploitation directly fuels a war economy,” it said.
International projects to provide transparency by tagging and tracing minerals from conflict zones have been a “clear failure,” it added.
In a response on Sunday night, M23 accused the Congolese government of ignoring a lengthy list of deadly mining accidents in government-controlled regions where M23 has no presence. It said the Rubaya disaster was a tragedy that resulted from “exceptional weather conditions.” The miners at the site were “forced to work in precarious conditions” because of poverty caused by the country’s mismanagement, it said.
The militia said it would take charge of burials for the dead and hospital treatment for the survivors. At least 20 survivors are reportedly being treated for injuries.
For years, the Rwandan government repeatedly denied that it has any link to M23. But last month, in a statement to a U.S. congressional subcommittee, Rwandan diplomats acknowledged for the first time that their government engages in “security co-ordination” with the M23 militia. They also confirmed that they are seeking a “security buffer” in eastern Congo.
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The UN investigators, however, have found evidence of much more extensive Rwandan military involvement. They estimate that Rwanda has sent 6,000 to 7,000 well-equipped soldiers and an arsenal of sophisticated weaponry into Congo to support M23’s operations. They have concluded that Rwanda has effective command and control of the rebel militia, making it a Rwandan proxy force.
In their latest report to the UN Security Council, released in early January, the investigators documented how M23 had created a parallel government to entrench its rule of eastern Congo, including two major cities, Goma and Bukavu.
The militia has also recently expanded into South Kivu province, where it controls the majority of critical-mineral production, including coltan, cassiterite and wolframite, the UN report said.
At one unofficial gold-mining site in the province, M23 imposes taxes on about 5,000 small-scale miners, it said.
The militia also took control of the region’s only industrial gold mine, Twangiza, which had been brought into production in 2012 by Toronto-based Banro Corp. and was later sold to Chinese investors, the report said.