The investigation into the alleged theft of state secrets by mining giant Rio Tinto employees would not affect China's cooperation with multinational companies, according to Foreign Ministry spokesman Qin Gang.

Four Shanghai-based employees of the Anglo-Australian miner, including an Australian executive born in China, were detained on July 5, accused of bribing steel officials to obtain secret data during tense iron ore price negotiations this year.

At a regular press briefing in Beijing yesterday, Qin reiterated that this was an independent judicial case that had seriously hurt China's economic security and interests.

"But this doesn't mean we want to restrict foreign companies' business in China or restrain the cooperation between Chinese and foreign companies," he said.

China has been the top destination among developing countries for global foreign direct investment for 17 years in a row.

Qin said China protected the legal rights of foreign investors in accordance with the law, while foreign firms should also respect the nation's laws.

Inquiry widened

Australian Prime Minister Kevin Rudd said yesterday his government was talking with China over the detention of Stern Hu, the Australian passport holder who heads Rio's iron ore operations in China.

Australian consular officials met Stern Hu last Friday in a Shanghai detention center where he is being held.

Qin also said an Australian newspaper report saying that President Hu Jintao personally endorsed the Rio inquiry was incorrect.

Meanwhile, China has widened the investigation to at least five domestic steel makers, as reported by Chinese media yesterday.

A chief negotiator for Baosteel Group was questioned but allowed to return to work, according to the 21st Century Business Herald.

The alleged secrets could relate to China's negotiating stance in the ore talks and mills' production and purchase plans, gross margins and ore stock levels.

Officials of the China Iron and Steel Association, which led China in this year's price talks, are also reportedly being investigated. Shan Shanghua, CISA's secretary general, has not answered calls to his cell phone for days.

Qin said relevant authorities were investigating "several related people," but he was not aware of specifics.

China is still negotiating prices with miners for iron ore prices.

A deadline passed on June 30, but an agreement may be reached before the end of the month, according to sources familiar with the situation. (Xinhua News)