Deloitte’s victory in winning the contract to audit the first full set of Western-standard financial statements of the company that operates the world’s largest gold mine—Navoi Mining and Metallurgical Company (Navoi, or NMMC), which runs the vast Muruntau mine in the deserts of Uzbekistan—could prove an embarrassment, according to The Sunday Times.

The UK daily reported on June 17 that “within months of its [Deloitte’s] audit for 2020 and 2021 being signed off last May, a report, by the rival PwC concluded that Navoi had been the victim of over-charging totalling hundreds of millions of dollars in its supply chain. They were caused, PwC said, by serious weaknesses in its procurement system”.

The PwC study was commissioned by Navoi’s supervisory board and seen by the Sunday newspaper. It reportedly outlined how Navoi purchased machinery from companies including digger giants Caterpillar and Komatsu through middleman companies that, despite competitive tendering, devised tricks, such as fake bids, to artificially inflate the sums Navoi was paying.

This, the report was said to have concluded, was because Navoi’s purchasing process created “false visibility of the market”. Between 2019 and 2022, PwC reportedly assessed, Navoi overpaid by between $380mn and $427mn.

However, Deloitte gave Navoi’s figures, showing an annual profit of $2.5bn, the all-clear.

The Sunday Times wrote that suppliers Komatsu and tyre company Michelin said they had hired law firms to conduct investigations after the newspaper brought the PwC report to their attention. In the cases of these two companies, the report alleged tender process manipulation by Uzbek company Trade Group and Dubai-based Empyrean Heavy Machinery Spare Parts Trading LLC.

An Empyrean spokesman was quoted as saying the company was aware of the findings, but declined to discuss specific allegations. Trade Group was reported as not replying to numerous attempts by the investigating reporters to contact it.

A Caterpillar spokeswoman was cited as saying: “Caterpillar believes fair competition is fundamental to free enterprise. We observe antitrust and competition laws where we do business. We are not involved in any arrangements, understandings or agreements with competitors affecting prices, terms upon which products are sold, or the number or type of products manufactured or sold.”

The PwC report was also reported as showing that Dubai company Empyrean supplied large quantities of Komatsu vehicles and equipment to Navoi, with one 2020 contract worth $41mn for the provision of Komatsu mining trucks—though Empyrean was, it was claimed, competing against several companies that did not submit tender proposals or submitted allegedly forged paperwork.

Komatsu hired the Washington office of law firm Reed Smith to investigate the issue. A representative of the law firm was quoted as saying: “Neither Empyrean nor Trade Group are Komatsu partners. Komatsu does not know or have any relationship with Empyrean or Trade Group… Prior to receiving the information [from The Sunday Times], Komatsu was not aware of Empyrean or any involvement by Empyrean in the supply of Komatsu equipment.

“Komatsu… is actively investigating the allegations. Komatsu will take appropriate action, if necessary, to ensure its continued compliance with all applicable laws.”

A spokesman for Michelin was reported as responding: “Michelin strongly forbids any violation of the laws in each country where we operate directly or indirectly, as stated in our codes of ethics and our anti-corruption code of conduct.”

When asked why Deloitte gave a clean bill of health to the Navoi accounts, a spokesman for the auditor in London was said to have replied: “Our professional standards prohibit us from commenting on entities we audit.”

A spokesman for Navoi declined to discuss the PwC report with the newspaper.

The Sunday Times stated that there was no suggestion of wrongdoing by Caterpillar, Salzgitter, Komatsu or Michelin.

Gold was first discovered at Muruntau in 1958. The mine spans 3.5km by 2.5km and produces 2mn ounces of gold a year.

The London arms of JPMorgan and Citi last year participated in a $1.2bn syndicated loan to help Navoi modernise.