China has reportedly indicted four Rio Tinto employees on charges of bribery and violating commercial secrets.
The indictment means they will now face trial. Rio Tinto has declined to comment on the report by Xinhua, the state news agency.
An Australian citizen Stern Hu, Rio Tinto's lead iron ore negotiator in China, is one of the four facing trial.
Mr Hu and his Chinese colleagues Liu Caikui, Ge Minqiang and Wang Yon have been in detention since July last year. If convicted, they could face up to 27 years in prison.
The prosecutor's office is quoted by Xinhua as saying the defendants used "personal inducements" and other improper means "many times" to obtain commercial secrets from Chinese steel companies.
The BBC reports Rio scrapped a $US19.5 billion deal with Chinalco in favour of a tie-up with BHP Billiton a month before the arrests.
The Australian government has not yet commented on the reports.