A Philippine plane warned a Chinese military helicopter over the South China Sea that it was "flying too close," as tension between the U.S. ally and Beijing soars.

The Philippine foreign ministry said on Friday it was "concerned" over what it described as "unsafe manoeuvres" and the use of flares by a Chinese air force plane against an Australian Air Force aircraft in the South China Sea.

Australia said Thursday that a Chinese fighter jet dropped flares near an Australian air force plane patrolling the South China Sea, accusing Beijing of “unsafe” military conduct. Beijing swiftly hit back,