BEIJING, China (CNN) -- China has leveled new allegations in the arrest of employees of one of the world's largest mining companies, saying Rio Tinto overcharged Chinese steel mills by $100 billion over six years.
Rio Tinto signage scrolls past the opening bell at the Australian Stock Exchange in Sydney on June 5.
The latest allegations, involving the sale of iron ore, appeared on a Web site affiliated with China's state secrets administration.
A spokeswoman for Rio Tinto said Monday that the company had heard about the new accusations but did not wish to comment on it.
Last month, China arrested four company employees on suspicion of stealing state secrets.
China said the four employees bribed executives from 16 of China's major steel mills to obtain industry information.
Rio Tinto has called the allegations surprising and said it was not aware of any evidence to support an investigation.
The company recently was involved in annual negotiations about supply contracts with Chinese mills.
The arrests come a month after Rio Tinto broke off a more than $19 billion investment deal with China state-owned Chinalco.
The deal with Chinalco was signed in February and was awaiting a review by Australia's Foreign Investment Review Board.
Rio Tinto has headquarters in London, England, and Melbourne, Australia.
The deal soured as opposition party members in Australia ratcheted disapproval, saying it would put Australian resources at strategic risk.
Others saw the deal as an alliance that would further link resource-rich Australia with the commodities-hungry Chinese market.
CNN's Jo Ling Kent contributed to this report.