Shanghai, July 9 (Xinhua) Four employees of the international mining group Rio Tinto Ltd. have been detained on charges of stealing China’s state secrets, authorities said Thursday.

The detained employees include Stern Hu, general manager of the company’s Shanghai office and also in charge of the iron ore business in China, according to the Shanghai municipal state security agency.

Hu, an Australian citizen of Chinese origin, was detained in Shanghai Sunday on allegations of espionage and stealing state secrets, Australian Foreign Minister Stephen Smith had said Wednesday.

The other three, who also worked in the Shanghai office and were detained on the same charges, were holding Chinese passports and the case was being investigated according to law, the authorities said.

“We have been advised by the Australian government of this surprising allegation,” Rio Tinto said in an e-mail statement to Xinhua Thursday. “We are not aware of any evidence that would support such an investigation.”

Rio Tinto said it would continue to work to support its employees and their families. It refused to comment further on the issue.

“Rio Tinto intended to cooperate fully with any investigation the Chinese authorities may wish to undertake and has sought clarification on what has occurred,” Ian Head, Rio Tinto spokesman said in an email statement to Xinhua Wednesday.

The iron ore giant is in talks with Chinese steel mills over the iron ore contract prices. The negotiations passed the June 30 deadline as Rio Tinto stuck to its offer of a 33 percent price cut for 2009-10 contracts, while the Chinese mills insisted on a deeper cut.

Rio Tinto has offices in Beijing, Shanghai and Guangzhou on the Chinese mainland.