Beijing yesterday warned Australia to "act prudently" or face "serious consequences" after Canberra accused a Chinese fighter jet of dangerously intercepting one of its spy planes over the South China Sea. Australia has argued it is not unusual for it to undertake surveillance flights in the South China Sea -- a region Beijing insists comes under its domain despite a 2016 Hague ruling that dismissed its claims. China's stance has heightened tensions with the United States and its allies, which insist on freedom of navigation in the area. Australian Defence Minister Richard Marles said Sunday that a Chinese J-16 fighter intercepted a P-8 surveillance aircraft late last month, in a "dangerous" manoeuvre that put the safety of the Australian Defence Force crew at risk. But Beijing hit back yesterday, saying it would "never allow any country to infringe upon China's sovereignty and security... under the pretext of freedom of navigation".