BEIJING: China has begun operating a lighthouse on one of its artificial islands in the South China Sea near which a US warship sailed last year to challenge China’s territorial  claims. China claims most of the energy-rich waters of the South China Sea, through which about $5 trillion in ship-borne trade passes every year. But neighbours Brunei, Malaysia, the Philippines, Taiwan and Vietnam also have claims. China’s transport ministry held a “completion ceremony”, marking the start of operations at the 55-metre high lighthouse on Subi Reef, where construction began in October, state news agency Xinhua said late on Tuesday. Subi Reef is an artificial island built up by China over the past year or so. Before Chinese dredging turned it into an island, Subi was submerged at high tide. Under the UN Convention on the Law of the Sea, 12-nautical-mile limits cannot be set around man-made islands built on previously submerged reefs.