Australian iron ore mining company BHP Billiton said the United States Defense Department was blocking it from using Lockheed Martin developed mapping technology to search for mineral deposits in China. Its Falcom system, first developed for the US Navy's submarine fleet, can be used to identify mineral deposits deep underground. The company acknowledged licensing terms allowed the US to restrict its use, and a Pentagon official confirmed the system was on the list of embargoed exports drawn up after the Tiananmen crackdown. Separately, 16 Chinese steel producers rejected BHP Billiton's call for a US$7.50 to US$10 per tonne surcharge on top of an agreed 71.5% price increase negotiated earlier as ore prices skyrocketed earlier in the year. China's industry association called the surcharge excessive.