Australia's government said on Saturday it had expressed serious concerns to China after an "unsafe and unprofessional" interaction between an Australian navy vessel and Chinese warship left Australian military divers injured.
Defence Minister Richard Marles said the HMAS Toowoomba - a long-range frigate - was conducting a diving operation in Japan's Exclusive Economic Zone on Nov. 14 to clear fishing nets from its propellers when the incident occurred.
"While diving operations were underway a PLA-N destroyer (DDG-139) operating in the vicinity closed towards HMAS Toowoomba," Marles said in a statement, referring to a ship of the People's Liberation Army Navy.
He said despite the Australian vessel notifying the Chinese warship of the diving operation and requesting that it keep clear, the destroyer approached "at a closer range".
"Soon after, it was detected operating its hull-mounted sonar in a manner that posed a risk to the safety of the Australian divers who were forced to exit the water."
The conduct was "unsafe and unprofessional", Marles said.
The Chinese embassy in Australia did not immediately respond to a request for comment.
Medical assessments found minor injuries to the divers likely caused by the destroyer's sonar, said the defence minister.
"Australia expects all countries, including China, to operate their militaries in a professional and safe manner," Marles said, adding that the safety and wellbeing of Australian military personnel was the government's "utmost priority".
China has emerged in recent years as an increasingly assertive power in the Indo-Pacific region, including upgrading security ties with Solomon Islands in July.
Earlier this year, Australia - a close United States ally -conducted two weeks of war games involving more than 30,000 troops with the U.S. in a show of force amid China's growing regional influence.
