Metal casing from a flare released by a Chinese jet near an Australian surveillance plane could have caused engine failure or even a crash had it struck the aircraft, an expert has said.
An incident in international airspace over the South China Sea between the nations was made public by Defence Minister Richard Marles on Monday amid fears Beijing is growing more aggressive in the contested region.
While occurrences of "unsafe and unprofessional" behaviour in the region are yet to result in a significant incident between Australia and China, the potential consequences of a flare striking a plane are severe.
"It could impact the blades, it could disrupt airflow, it could start a fire," security analyst and academic Jennifer Parker told AAP.
"A catastrophic engine failure or fire could, in the worst circumstances, result in that plane crashing."
While the exact location of the planes at the time of the incident has not been released, Marles reiterated on Tuesday the planes were in international airspace at the time.
"At every moment our crew was adhering to international law," he told reporters in Adelaide.
A spokesperson for the People's Liberation Army refuted the Australian government's claim, saying the RAAF P-8A Poseidon "intruded" into Chinese airspace.
"The troops in the theatre are on high alert at all times to resolutely defend national sovereignty," Senior Colonel Li Jianjian said in a statement.
China's claim to the Paracel Islands, where the incident is believed to have occurred, was not legitimate and Australia had operated militarily in the region for decades, Parker said.
"Their claims that we are impeding on their airspace are not consistent with international law," she said.
"I don't agree with China's claims whatsoever, in fact, most countries don't agree with China's claims when it comes to the South China Sea."
The RAAF aircraft was carrying out a routine patrol on Sunday when the People's Liberation Army jet flew alongside it, Marles previously said.
On two occasions the Chinese aircraft released flares "very close" to the Australian plane, he said.
"We have made our position very clear to China, both through our embassy in Beijing but also to the Chinese embassy in Canberra," Marles said on Tuesday.
Despite the recovery of the Australia-China relationship on economic and diplomatic terms under the Albanese government, Parker said such incidents highlight how aggressive China was still prepared to be.
It was crucial Australia continued to maintain a military presence in the South China Sea because of its importance as a trade route for the Australian economy, she added.
"Our national security interests are directly at odds with China's national security interests," Parker said.
"The security relationship between the two countries is not stabilised and is not about to stabilise.
Australia should continue to improve military-to-military communication with China to prevent similar future incidents, according to Lowell Bautista, a Western Sydney University an expert in the law of the sea.
The government should reaffirm Australian military operations were protected under international law and intended to uphold regional peace rather than undermine it, Bautista said.
"Australia's message should be clear: we seek peace, not provocation."
