(Reuters) - The U.S. Securities and Exchange Commission is examining claims from a whistleblower that Rio Tinto (AX:RIO) was aware of problems at its underground copper mine extension project of Oyu Tolgoi in Mongolia months before the miner confirmed the project would face delays and higher costs, the Financial Times reported https://on.ft.com/3h4XQeb on Sunday.
The SEC is probing allegations made by Richard Bowley, a British national who worked for the company's copper business in Mongolia between 2017 and 2019, the newspaper said, citing people with knowledge of the situation.
The U.S regulator has not yet decided to launch an investigation, the newspaper added.
In July, Rio Tinto said it cut estimated reserves at its underground copper mine extension of Oyu Tolgoi and confirmed it would face delays and higher costs after ground instability forced it to redesign the mine plan.
Oyu Tolgoi (OT) is Rio's biggest copper growth project but has faced geological challenges.
The SEC was not immediately available for Reuters' request for comment.