At least 2,000 tonnes of uranium may have left the Democratic Republic of Congo for China since 2000, despite the country not officially producing the radioactive material, according to an international investigation.
The estimated quantity would theoretically be sufficient to produce around 600 nuclear warheads, although the uranium was allegedly exported as a contaminant or byproduct of Congo’s vast cobalt industry rather than as declared nuclear material.
The findings were produced by investigative outlet Lighthouse Reports, the Financial Times and researchers from the universities of Wisconsin–Madison and Princeton. The research was also published in the scientific journal Nature Communications and reported by France’s Le Monde newspaper.
According to the investigation, the material left Congo without oversight from the International Atomic Energy Agency, with China identified as the principal destination because it processes the overwhelming majority of Congolese cobalt.
Uranium hidden within cobalt exports
Congo’s uranium history is closely associated with the Shinkolobwe mine, which supplied material used in the Manhattan Project during the Second World War.
Under a 2005 presidential decree, uranium is classified as a reserved resource in the country, making its commercial exploitation illegal.
However, concerns about undeclared exports have persisted for years. A 2007 diplomatic cable from the US Embassy in Kinshasa reportedly warned that uranium-rich cobalt could be exported to Europe.
An internal IAEA memorandum written in 2009 also cited what it described as credible information that uranium was already being exported as a byproduct of cobalt production.
Uranium occurs naturally alongside cobalt in parts of Congo’s mineral-rich soil. Congo is the world’s leading producer of cobalt, a key material used in lithium-ion batteries for electric vehicles and other technologies.
During cobalt processing, uranium must be removed, usually with phosphoric acid, to bring radiation levels below legally permitted thresholds.
Congolese authorities formally impose radiation limits on mineral exports, and shipments exceeding those limits can be quarantined. However, officials lack the capacity to inspect every truck leaving the country.
Steve Mwanza, the head of Congo’s General Atomic Energy Commission, has called for radiation detectors to be installed at border crossings to help combat uranium smuggling.
Mining companies faced contaminated shipments
Customs data examined by investigators suggested that only two major mining groups — Eurasian Resources Group and Glencore — imported enough phosphoric acid in recent years to consistently keep uranium concentrations below Congo’s legal limit.
Both companies were forced to suspend production at separate mines in 2018 after elevated uranium levels were detected in cobalt shipments.
Chinese mining company Zijin reportedly began using phosphoric acid only in 2024, after one of its shipments was returned because of excessive radiation.
Using geological data on uranium concentrations and estimates of how cobalt refining affects those levels, researchers concluded that at least 2,000 tonnes of uranium could have left Congo between 2000 and 2024.
Hundreds of pages of internal company documents also indicated that uranium-rich cobalt was produced between 2015 and 2021.
One internal table showed uranium present throughout the production process, from raw material to finished cobalt products, between June 2016 and December 2020.
In one batch recorded on December 14, 2016, uranium concentrations exceeded 0.1%, around 15 times the limit permitted by Congolese authorities.
China identified as likely destination
The investigation said large quantities of uranium appear to have crossed Congo’s borders in recent years, raising questions about what happened to the radioactive material after contaminated cobalt reached overseas processing facilities.
China imported more than 95% of Congo’s cobalt output in 2025, according to commodities consultancy Darton Commodities.
Because radioactive contaminants must be removed before cobalt can be used industrially, researchers and nuclear experts said it was possible that uranium was being recovered during processing in China.
Olli Heinonen, a researcher at the Stimson Center and former IAEA deputy director general for safeguards, said such recovery was technically possible.
Mwanza said he would be surprised if Chinese processors were not extracting all usable materials from imported ore, arguing that mining investors generally seek to maximise the value of every shipment.
David Albright, a physicist and founder of the Washington-based Institute for Science and International Security, also said China was known to recover uranium from cobalt.
China’s Ministry of Industry did not respond to requests for comment, according to the investigation.
A 2023 article published in the Chinese journal Modern Mining, written by engineers and executives from state-owned mining companies operating in Congo, called for the efficient recovery and use of uranium contained in Congolese cobalt, describing it as strategically important.
China’s nuclear power plants consumed close to 10,000 tonnes of uranium in 2022, according to estimates published by Chinese researchers in 2025.
Domestic production reportedly covers less than 20% of the country’s requirements, leaving China heavily dependent on imports.
The researchers warned that China’s reliance on foreign uranium could reach 90% by 2030, exposing its nuclear energy programme to disruptions in overseas production and supply.