Australia has accused a Chinese military aircraft of releasing flares "in close proximity" to its patrol jet over the South China Sea.

The Australian government has raised its concern with Beijing over the "unsafe and unprofessional" manoeuvre, the defence department said in a statement on Monday.

There was no damage to Australia's P-8A aircraft and its personnel were unharmed after Sunday's encounter.

A Chinese military spokesperson said the Australian jet "illegally intruded" into China's airspace and had to be expelled.

The Australian aircraft's actions "seriously infringed upon China's sovereignty," Senior Colonel Li Jianjian, spokesperson for China's Southern Theater Command Air Force, said, urging Canberra to "immediately cease its infringing and provocative actions."

Australia Defence Force said it expects all countries, including China, to operate their militaries in a safe and professional manner.

This is the latest in a string of encounters between the two countries' militaries in the region, where China's vast claims over islands and outcrops overlap with those of its neighbours.

Sunday's incident also occurred as Australian Prime Minister Anthony Albanese was heading to the US for a meeting with President Donald Trump, where the two leaders are expected to discuss Aukus—a multi-billion dollar submarine deal between Australia, the US and the UK.

Australia has also accused a Chinese jet of dropping flares near an Australian plane in the area in February. China at that time said the Australian jet had intentionally intruded into its airspace and that its response was "lawful and restrained".

While it has no claims to the South China Sea, Australia has aligned itself closely with the US and its allies in saying that China's assertions have no legal basis.

In May last year, Australia accused a Chinese fighter plane of dropping flares close to an Australian navy helicopter that was part of a UN Security Council mission on the Yellow Sea off the Korean coastline.

In November 2023, Canberra accused Beijing's navy of using sonar pulses in international waters off Japan, which resulted in injuries to Australian divers.