Beijing demanded an end to U.S. surveillance near China on Thursday after two of its fighter jets carried out what the Pentagon said was an "unsafe" intercept of a U.S. military reconnaissance aircraft over the South China Sea.

The incident, likely to increase tension in and around the contested waterway, took place in international airspace on Tuesday as the plane carried out "a routine U.S. patrol," a Pentagon statement said.

A U.S. Defense official said two Chinese J-11 fighter jets flew within 50 feet (15 meters) of the U.S. Navy EP-3 aircraft. The official said the incident took place east of Hainan island.