Australia's prime minister accused Beijing of "unacceptable" conduct Tuesday, following reports a Chinese fighter jet fired flares in the flight path of an Australian navy helicopter over international waters. 

The helicopter was flying across the Yellow Sea on May 4 as part of United Nations' efforts to enforce sanctions on North Korea, Australia's Defence Department said late Monday evening. 

Defence officials said it was soon "intercepted" by a Chinese warplane, which endangered the helicopter by firing flares across its flight path. 

"We've just made it very clear to China that this is unprofessional and that it's unacceptable," Prime Minister Anthony Albanese told Australia's Nine Network on Tuesday. 

"I think the Australian public would expect some form of explanation about how this could occur." 

Albanese said Australia's concerns had been raised through diplomatic and military channels, although Beijing had yet to respond. 

Canberra in November said a Chinese destroyer had injured submerged Australian navy divers by deliberately blasting them with sonar pulses. 

Beijing's foreign ministry insisted at the time that China's military "always conducted professional operations in accordance with international law". 

Albanese made a breakthrough trip to China last year, hailing mended trading relations after years of bickering and reprisals. 

But tensions remain when it comes to security, as Australia draws closer to the United States in an effort to blunt China's expanding influence in the Asia-Pacific region.