Four Rio Tinto executives, including Australian Stern Hu, faced charges of stealing commercial secrets in China on Tuesday, the second day of a trial that has already brought confessions to taking bribes.

Hu and three Chinese employees of giant miner Rio — Liu Caikui, Ge Minqiang and Wang Yong — contend the amount of kickbacks they took were far lower than the sums alleged by prosecutors, lawyers and domestic media said.

The four could face jail terms of up to 20 years on the bribery charges alone.

Tao Wuping, a lawyer for the accused Liu, said the commercial secrets charges would probably be heard on Tuesday afternoon, but declined to say how his client would plead.

“This morning we’ll be arguing all aspects of the charges,” said Zhai Jian, the lawyer for Ge, saying he was unsure when the trial would move to the commercial secrets charges.

“Everyone will speak. There are eight lawyers, so I can’t predict when this session will be finished,” he said.

The trial is taking place at a time when foreign business sentiment is souring against China.

Google Inc. said on Monday it would redirect users of its mainland Chinese-language search engine to one based in Hong Kong, ending self-censorship demanded by Beijing.

Rio has said the four did nothing wrong.

Rio chief executive Tom Albanese told an audience in Beijing on Monday he did not want to jeopardise business ties with China, the world’s biggest consumer of iron ore.

“This issue is obviously of great concern to us,” he said.

Rio Tinto has not officially commented on the guilty pleas by its employees, but its iron ore division chief, Sam Walsh, said in Perth on Tuesday China remains a preferred partner in future projects for the world No. 2 iron ore producer.

Canberra has protested China’s exclusion of Australian diplomats from watching the part of the trial about commercial secrets, saying they have the right to be present for the whole trial, scheduled to last until Wednesday.

Shanghai is likely to want the case over quickly, before its much ballyhooed 2010 World Expo opens in May.

The case has thrown an unwelcome spotlight on China’s often murky marketplace, where legal boundaries can be vague and courts closely tied to the state, creating pitfalls for businesses seeking profits in the world’s third-biggest economy.

The four employees from Rio’s iron ore team were detained last July at the height of fraught annual price negotiations over iron ore, the main raw material for steel.

China’s industry, the world’s largest, is rent between the most powerful mills, who buy iron ore from Rio and other miners at relatively lower term prices, and the medium sized mills, who fight to secure ore at any price in order to stay large enough to stave off mergers with bigger state-owned firms.

Industry sources said desperate mills would offer cash to ensure they got their term allocations whenever Rio reduced term supply or diverted cargoes to the pricier spot market.

Tom Connor, the Australian Consul General in Shanghai who attended the hearing, told reporters on Monday that Hu, an Australian citizen, was accused of taking bribes worth 1 million yuan ($146,500) and $790,000.

Lawyers for the three Chinese defendants said they also acknowledged taking bribes, but maintained the amount of the kickbacks alleged by prosecutors was inflated.

Wang Yong, who is charged with the largest amount of bribes, or 70 million yuan, called for testimony from Du Shuanghua, the billionaire founder of Rizhao Steel, to contest bribery allegations for $9 million of that charge, the National Business Daily reported.

Du testified that he had given Wang the $9 million in appreciation for his support for Rizhao, one of China’s most aggressive mid-sized steel mills. Du last year lost his fight to keep Rizhao independent, and sold a majority stake to the state-backed Shandong Iron and Steel Group.

Two executives from two other Chinese mills, Shougang and Laiwu Steel, have been in custody since the summer. They were named in the prosecutor’s case, media said.

(Additional reporting by Royston Chan and Shen Rujun; Editing by Ken Wills and Bill Tarrant)