The world’s largest mining company, Australia’s BHP Billiton, is closing its Beijing office and halting exploration of metal deposits in China, Bloomberg reported. A spokeswoman said China has not been a core focus of the company’s exploration. BHP will keep a marketing office in Shanghai. BHP has been exploring in China for 15 years for major deposits of iron ore, copper and coal to meet demand in China, which is its single largest customer nation. China’s government last year revised rules that restricted foreigners from investing in copper, lead, zinc and other base metal mines, to protect what it regards as scarce resources. A Beijing-based BHP official declined to comment on government policies but said his company failed to find large, low-cost and long reserve-life resources in China.