Australia said Saturday it had expressed serious concerns to China over an "unsafe and unprofessional" interaction between Australian naval divers and a Chinese warship earlier this week, which resulted in minor injuries.

Australian Defense Minister Richard Marles said in a statement the incident occurred Tuesday when Australia's Toowoomba, a long-range frigate, was conducting diving operations to clear fishing nets from its propellers in international waters inside of Japan's exclusive economic zone.

Photo taken in September 2023 shows Toowoomba (front), a long-range frigate of the Royal Australian Navy. (Photo courtesy of Australian Department of Defence)(Kyodo)

A People's Liberation Army Navy destroyer operating in the vicinity approached the vessel and began using its hull-mounted sonar, despite the Australian frigate signaling its intention to conduct diving operations and requesting the ship keep clear, Marles said.

Marles said the sonar was used "in a manner that posed a risk to the safety of the Australian divers who were forced to exit the water" and they had sustained minor injuries likely caused by the sonar pulses.

"Australia expects all countries, including China, to operate their militaries in a professional and safe manner," Marles added.

The incident comes less than a fortnight after Australian Prime Minister Anthony Albanese made the first visit to China by an Australian leader in seven years, amid improving relations between the two countries after years of heightened tensions under the government of his predecessor, Scott Morrison.

China has become increasingly assertive in the Indo-Pacific region in recent years, as it seeks to expand its sphere of influence with moves such as signing a wide-reaching security agreement with the Solomon Islands last year.

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