China tests Rio Tinto's mettle

China today charged four employees of mining firm Rio Tinto with ­bribery, thereby quashing the comforting notion that a highly sensitive case could be defused behind closed doors by the diplomats. Rio, for now at least, is obliged to maintain its public faith in Chinese justice. Anything else might jeopardise the position of its detained employees, who include Stern Hu, an Australian national. The softly-softly approach, however, would clearly have to be abandoned if Hu and the others were convicted, since Rio's unswerving stance has been that the detained employees "acted at all times with integrity and in accordance with Rio Tinto's strict and publicly stated code of ethical behaviour". Rio's public statements to date have also made a point of mentioning that the company continues to ship high ­levels of iron ore to China from ­Australia. The implication, one assumes, is that it would stop shipments if the four were convicted. Frankly, no other policy would be credible. Such drama is still a long way off but the stakes are rising. Last summer, it looked as if China, peeved by the ­collapse of its $20bn deal to invest in Rio, was merely trying to secure a lower price for its iron ore imports. It's far more serious than that.