Chinese Navy Drills in Tasman Sea Unnerve Australia and New Zealand

Chinese warships that have been sailing south along the eastern coast of Australia gave notice on Friday of their intent to conduct live fire exercises in international waters between Australia and New Zealand, forcing commercial flights to divert and putting the two countries on edge.

The three naval vessels, which include one of the most powerful warships in the Chinese navy’s fleet, were outside Australia’s exclusive economic zone when the drills took place, Prime Minister Anthony Albanese of Australia told reporters.

The ships were first detected in the region last week, according to Australian officials.

While the Chinese vessels appeared to have acted in accordance with international law, the Australian and New Zealand militaries were closely monitoring them, Mr. Albanese said. He said it was not immediately clear what, if any, live fire drills were conducted Friday.

Analysts have said that the unannounced presence of the warships near Australian territorial waters — thousands of miles away from the Chinese mainland — was a show of force.

In Beijing, a spokesman for China’s foreign ministry described the actions of the ships as “far seas exercises.” They were organized by the People’s Liberation Army’s Southern Theater Command, which also oversees the navy’s activities in the South China Sea.

“The drill was carried out in a safe, standard and professional manner in accordance with relevant international law and international practice,” the spokesman, Guo Jiakun, said.

Airservices Australia, which manages air traffic in the region, said in a statement that it had advised airlines and radioed pilots with planned flights to avoid parts of the Tasman Sea “as a precaution.”

Australia’s foreign minister, Penny Wong, said that she was concerned about the lack of “transparency” in relation to the exercises and the notice given Friday, and said she would raise it with her counterpart, Wang Yi. They were scheduled to meet later Friday at the G20 meeting in South Africa.

The ships, a guided missile cruiser, a frigate and a supply vessel, were first detected off Australia’s northeast coast last week. This week, they passed through waters about 150 nautical miles from Sydney, well outside Australia’s territorial waters but inside its exclusive economic zone.

Australian officials have stressed that the Chinese ships have been traversing regional waters legally, but that they were closely monitoring their movements.

Li You contributed research.