According to Mining Weekly, Australia and China have exchanged warnings regarding the detention of mining company Rio Tinto employees for spying. The United States called on the Beijing government to ensure fair treatment for staff working for foreign companies.

A week after the detention of an Australian Rio executive and three Chinese nationals also employed by giant miner Rio Tinto on allegations of espionage related to iron-ore price negotiations, China's Foreign Ministry told Australia to back off.

Mining Weekly quotes ministry spokesman Qin Gang: "We resolutely oppose anyone deliberately whipping up this case or trying to interfere in China's judicial independence. This is not in Australia's interest."

Australian Foreign Minister Stephen Smith issued his own warning: "China itself does need to think about whether its handling of this matter has any adverse implications for it."

On Thursday, Smith and Chinese officials met at the site of the Non-Aligned Movement summit in Egypt's Red Sea resort of Sharm el-Sheikh, but neither side offered any comment.

Separately, US Commerce Secretary Gary Locke pointed out that the detentions of Rio Tinto employees indicate how the general opaqueness regarding state secret laws and what may be defined as potentially sensitive economic information put foreign nationals at risk.

Locke stated: "These are of course of great concern with respect to US investors and multinational companies from around the world that have projects here. We need to have transparency, we need to have assurances and confidence that people working for these multinational companies will be treated fairly."

In the meantime, Sam Walsh, CEO of Rio Tinto’s Iron Ore Division, said: “Rio Tinto believes that the allegations in recent media reports that employees were involved in bribery of officials at Chinese steel mills are wholly without foundation. We remain fully supportive of our detained employees, and believe that they acted at all times with integrity and in accordance with Rio Tinto’s strict and publicly stated code of ethical behavior.”

Giant miner Rio Tinto continues to operate in China and is maintaining high levels of iron ore shipments from Australia.