China claims most of the energy-rich waters of the South China Sea, through which about $US5 trillion ($A6.6 trillion) in ship-borne trade passes every year. But neighbours Brunei, Malaysia, the Philippines, Taiwan and Vietnam also have claims.

State media reports that construction of the Zhubi Lighthouse began in October 2015. The 55-metre-high lighthouse, with a lantern of 4.5 metres in diameter on the top and rotating lights inside, is monitored through a Beidou remote control terminal.

China’s transport ministry says a “completion ceremony” has been held, marking the start of operations.

The US guided missile destroyer USS Lassen sailed within 12 nautical miles of Subi Reef in late October, drawing an angry rebuke from China, which called it “extremely irresponsible”.

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 United Nations Convention on the Law of the Sea, 12-nautical-mile limits cannot be set around man-made islands built on previously submerged reefs.

China says much of its construction in the South China Sea is designed to fulfil its international obligations in terms of maritime safety, search and rescue and scientific research.

China has lighthouse projects on two other reefs in the area – Cuarteron Reef and Johnson South Reef.

– with other agencies