Stern Hu, Rio Tinto's leading iron ore salesman in China, admitted taking bribes in a partly open hearing held March 22-24 in Shanghai.

The guilty pleas may be an embarrassment for Rio, which has been saying its employees are innocent and is again involved in tough iron ore price negotiations with China.

Rio Chief Executive Tom Albanese said in Beijing that he did not want to jeopardize business ties with China.

"This issue is obviously of great concern to us," Albanese said. "I can only say we respectfully await the outcome of the Chinese legal process."

"We remain committed to strengthening our relationship with China, not just because you our biggest customer, but because we see long-term business advantages for both of us," Albanese said.

The four employees from Rio's iron ore team, including Hu, were detained last July when Rio was acting as lead negotiator for global iron ore suppliers in price talks with Chinese steel mills. Hu was Rio Tinto's senior executive in China in charge of iron ore.

The four were also accused of seeking information about Chinese mines and mills.