By Rhiannon Hoyle
A Rio Tinto-controlled company has asked law enforcement to help with an internal investigation into allegations of corruption and unethical conduct at the giant Oyu Tolgoi copper operation in Mongolia.
The probe is the latest twist in a saga to develop and mine one of the world's biggest copper and gold deposits, found in the southern Gobi Desert, about 50 miles north of the border with China.
"We are aware of allegations involving procurement-related activities," Oyu Tolgoi LLC said in a statement. The company is "conducting a comprehensive internal investigation" and has "sought cooperation of law enforcement authorities."
It said it couldn't comment further given the probe is ongoing.
Oyu Tolgoi is 66% owned by Rio Tinto, while the government of Mongolia owns the rest. Rio Tinto manages the operation, which it expects to become the world's fourth-largest copper mine by 2030.
The operation is at the heart of Rio Tinto's plans to grow and diversify its portfolio away from steel ingredient iron ore, which it currently relies on for the bulk of its earnings. Increasing copper output is a priority for many of the world's biggest miners given the metal is used heavily to build electric cars, renewable energy and data centers.
Rio Tinto, the world's second-biggest miner by market value, has invested billions of dollars in an underground expansion of the Oyu Tolgoi mine, where it expects production will increase by more than 50% this year. More than 80% of Oyu Tolgoi's total value lies deep underground, according to the miner.
The development of Oyu Tolgoi, established as an open-pit mine in 2011, has been beset by delays, cost overruns and complicated negotiations with Mongolia's government, including a multiyear dispute over taxes.
In June, Rio Tinto agreed to pay $138.75 million to resolve a U.S. class-action lawsuit that alleged the company concealed problems during the expansion underground. The company agreed to the settlement to avoid the uncertainty of continued litigation, according to the court documents, and denied all allegations of wrongdoing.
Earlier this year, Oyu Tolgoi said it had faced "false and defamatory allegations" related to its procurement processes via some media and online platforms. In a statement published to its website in February, the company described its procurement processes as transparent and fully compliant with Mongolian laws and regulations.
"No single individual has unilateral decision-making authority over procurement and our operations are subject to [regular] audits by both national and international bodies," Oyu Tolgoi said in that statement.
Write to Rhiannon Hoyle at rhiannon.hoyle@wsj.com
(END) Dow Jones Newswires
October 27, 2025 00:39 ET (04:39 GMT)
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