Two Chinese J-11 tactical jets carried out an “unsafe” intercept of a US EP-3 reconnaissance aircraft that was conducting a routine mission in over the South China Sea, a US defence official said.

The Chinese jets came within 50 feet of the US aircraft at one point, the official told CNN.

The incident took place on Tuesday.

“We have made progress reducing risk between our operational forces and those of the People’s Republic of China by improved dialogue at multiple levels under the bilateral Confidence Building Measures and the Military Maritime Consultative Agreement,” Jeff Davis, a Pentagon spokesman, said.

“We are addressing the issue through the appropriate diplomatic and military channels,” he said.

Another defence official said this type of incident is not something the US military frequently sees in that region with Chinese aircraft.

Incidents with Russian aircraft in the Black Sea that have been well documented over the past year are much more common.

This is an incident that “definitely has people’s attention” at the Pentagon, he added.