China has started operating two lighthouses on a reef on the disputed Spratly Islands in the South China Sea - stressing the move is out of concern for civilian safety - even as the United States continues to consider sending its warships close to China's artificial islands in the region. The 50-metre-tall Huayang and Chigua lighthouses on Huayang Reef would improve navigational safety for ships, foreign ministry spokeswoman Hua Chunying said. The structures would address a severe shortage in navigational aids and maritime emergency and oil-spill response forces that had "immensely hindered the navigational safety and economic and social development" in the South China Sea, Xinhua reported yesterday. Beijing would "continue to build other civil facilities on occupied island reefs in the Nansha Islands", Hua said, using the Chinese name for the Spratlys. The activation of the lighthouses comes days after news that Washington was mulling sending ships within the next two weeks to waters inside the 12-nautical-mile zone that Beijing claims as territory around islands built in the Spratly chain. The Spratlys - mostly barren islands believed to be atop oil and natural gas deposits - straddle one of the world's busiest sea lanes. They are also claimed by Taiwan, Malaysia, the Philippines, Vietnam and Brunei. "Beijing's move is aimed at safeguarding navigational safety," said Professor Wang Hanling, marine affairs and international law expert at the Chinese Academy of Social Sciences. "It's an international service for fisheries, rescue missions and commercial ships." Shanghai-based naval expert Ni Lexiong agreed: "China is sending a message of peace amid heightened tensions … The lighthouses are purely for civilian use; they have no military value in modern wars." Tensions have been rising as the US and China's neighbours grow increasingly concerned about Beijing's maritime ambitions. Beijing lays claim to virtually the entire South China Sea. The US and the Philippines - worried that China's land reclamation around reefs and atolls could be used to base military equipment to intimidate other claimants and threaten freedom of navigation - have called for a freeze on such activity. China bristles at what it sees as US interference and says it is within its sovereign rights to develop islands made from sand piled on top of reefs and atolls.