Four Rio Tinto employees based in China have been indicted and are to face trial in a Shanghai court, the company announced Thursday. A trial date has not yet been set for the employees, who were arrested on suspicion of illegally obtaining commercial secrets and bribery and have been held in custody since July 5, 2009.

“We are very concerned about the nature of these charges, however, as this is part of an ongoing legal process, it is inappropriate to comment any further,” said Sam Walsh, chief executive Rio Tinto Iron Ore,

Rio Tinto stated its continued hope for “a transparent and expeditious process for its employees,” noting that senior managers from the company maintain regular contact with and provide support to the families of the detained employees.