(CNN) -- The Australian government has asked the Chinese government to treat the bribery case against four Rio Tinto employees "transparently and expeditiously."
The employees of mining giant Rio Tinto -- including an Australian citizen --have been formally charged with bribery, Chinese state media reported, in a case that has sent shockwaves through the foreign business community in China.
The Australia Department of Foreign Affairs and Trade received formal confirmation Thursday that the case was transferred to the Shanghai courts and the four face charges of receiving bribes and stealing commercial secrets.
"We are not in a position to say when the trial will commence or the duration of the trial," the Australian foreign ministry said in a statement posted on its Web site.
Prosecutors in Shanghai have charged Australian citizen Stern Hu, former head of Rio Tinto's Shanghai office, and three local employees, Wang Yong, Ge Minqiang and Liu Caikui, of bribery charges, Xinhua news agency reported Wednesday. The four have been held since July and were initially detained on charges of stealing state secrets.
"We are very concerned about the nature of these charges, however, as this is part of an ongoing legal process, it is inappropriate to comment any further," Sam Walsh, chief executive of Rio Tinto Iron Ore, said in a statement.
"Senior managers from Rio Tinto continue to maintain regular contact with the families of the detained employees and provide support to them," the statement read.
Prosecutors accused the men of "taking advantage of their position to seek profit for others, and asking for, or illegally accepting, huge amounts of money from Chinese steel enterprises," according to Xinhua.
The case has raised tensions between Australia and its largest trading partner, China. The July arrests came just after Rio Tinto broke a $19.5 billion investment deal with Chinalco against a backdrop of political concerns in Canberra about Chinese ownership of Australian natural resources.
Rio Tinto, which has headquarters in Australia and the UK, is the second largest mining company in the world.
Australia's vast commodities trade with China helped Australia become one of the few western nations to escape recession during the global financial crisis. Australia is a key supplier of iron ore to China for its burgeoning steelmaking industry.