Navy Commander Bill Urban, a Pentagon spokesman, said the United States regularly conducts B-52 training missions throughout the region but there was no plan for the B-52 to fly within 12 nautical miles of any artificial island.

China's defence ministry said in a statement on its website today that its forces had closely monitored the plane and warned the aircraft to leave.

Referring to the maneuver as 'provocation', the ministry said it urged the United States "to immediately adopt measures to put an end to such kind of dangerous actions, in order not to impact the two countries' military relations''.

The US guided missile destroyer USS Lassen sailed within 12 nautical miles of Subi Reef in late October to deliberately challenge China's claims of territorial waters there. The decision drew an angry rebuke from China, which called it 'extremely irresponsible'.

The incident involving the B-52 bomber took place last week near the Cuarteron Reef in the Spratly Islands, disputed territory claimed by China and several of its neighbors, the Wall Street Journal said.

Latest News from World News Desk