A Chinese jet fighter has dropped flares in front of an Australian Navy helicopter in international waters, in an incident Defence Minister Richard Marles has condemned as unprofessional and unacceptable.

9News can reveal the near-catastrophic incident occurred about 7.30pm (AEST time) on Saturday during a routine operation in the Yellow Sea off South Korea.

A Navy Seahawk operating off HMAS Hobart was intercepted by a Chinese J10 Air Force jet.

“The PLA Air Force plane dropped flares about 300 metres in front of the Seahawk helicopter about 60 metres above it, requiring the helicopter to take evasive action in order to not be hit by those flares,” Marles told 9News.

Defence sources have told 9News only the quick reflexes of the Australian pilot averted disaster – the Seahawk normally operates with a crew of four to six.

Marles condemned the incident and said Beijing had been formally notified of Australia’s concerns.

HMAS Hobart was taking part in Operation Argos, a United Nations mission to prevent North Korea smuggle sanctioned goods across the high seas.

“This was an incident which was both unsafe and unprofessional,” Marles said.

“Now Australians are engaging in important work enforcing UN Security Council sanctions and in doing that work, we’re operating on the high seas in accordance with international law in accordance with the UN Convention on the Law of the Sea.

“And we expect that when we have interactions with other militaries, including with the Chinese military that those interactions are professional, and safe. This incident was completely unacceptable.

“We have expressed our concerns to the Chinese government formally in relation to this incident. HMAS Hobart continues in its work in enforcing those UN Security Council sanctions.”