Beijing described the manoeuvres as training exercises that were "safe, standard and professional" and in line with international law, without commenting on whether live ammunition was used.

Australia's defence forces, joined by close ally New Zealand, have been monitoring the Chinese navy vessels -- a frigate, a cruiser and a supply tanker -- since they were spotted last week.

Defence Minister Richard Marles said China gave a warning that the vessels intended to engage in live firing as they sailed about half way between Australia and New Zealand in the Tasman Sea.

"By that I mean a broadcast that was picked up by airlines or literally planes that were commercial planes that were flying across the Tasman," he told national broadcaster ABC.

The Chinese naval ships were in international waters and acting within international law, Marles said, but Australian warships would typically give 12-24 hours' notice of such drills to give airlines time to react.

"That notice was not provided here," the defence minister said.

"This was very disconcerting for the planes that were flying, but they were able to divert," he said, stressing that the aircraft had not been placed in danger.

Australia had made representations to China both in Canberra and in Beijing asking why the purported live fire drills were held there and why more notice was not given to avoid disruption, Marles said.

The government was still awaiting confirmation that live firing actually took place, he said.

Australian Prime Minister Anthony Albanese confirmed there had been "no imminent risk of danger" to Australian or New Zealand assets.

Asked about the drills on Friday, China's foreign ministry said the country's military had "organised a naval formation to conduct training and exercises in distant waters".

- Commercial fights change course -

"The exercises were conducted in a safe, standard, and professional manner at all times, in accordance with relevant international laws and practices," ministry spokesman Guo Jiakun said at a regular press briefing.

Australia's air safety agency warned commercial flights to alter their course after receiving "reports of live firing in international waters".

"As a precaution, we have advised airlines with flights planned in the area," government agency Airservices Australia said in a statement.

"We are also working together to coordinate advice to operators and pilots."

Qantas and its subsidiary budget airline Jetstar temporarily adjusted some flights between Australia and New Zealand, industry sources said.

Virgin Australia was also heeding the advice, while Air New Zealand said it had "modified flight paths as needed to avoid the area".

The ships were reportedly within 150 nautical miles (around 280 kilometres) of Australia's mainland earlier this week.

Last week, Canberra rebuked Beijing for "unsafe" military conduct, accusing a Chinese fighter jet of dropping flares near an Australian air force plane patrolling the South China Sea.

Beijing swiftly hit back, accusing the Australian plane of "violating Chinese sovereignty and endangering Chinese national security".

It was the latest in a string of tense encounters between China and Australia in the increasingly contested airspace and shipping lanes of the Asia-Pacific region.

A Chinese fighter jet was accused of intercepting an Australian Seahawk helicopter in international airspace in 2024, dropping flares across its flight path.

In 2023, a Chinese destroyer was accused of bombarding submerged Australian navy divers with sonar pulses in waters off Japan, causing minor injuries.

The United States and allies including Australia frequently cross through the 180-kilometre (112-mile) Taiwan Strait to reinforce its status as an international waterway, angering China, which claims jurisdiction over the waters.

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