Australia's military was not notified before the Chinese navy started "irresponsible" live-fire drills in the Tasman Sea, finding out after a Virgin pilot relayed the warning, the Defence Force chief says.
Admiral David Johnston told a parliamentary hearing on Wednesday New Zealand's military had been monitoring the warships and didn't inform the Australian Defence Force until about an hour after the pilot reported it to civil aviation authorities.
Airservices Australia became aware of the risk at 9.58am on Friday and alerted Defence about 10 minutes later.
But the Chinese military's window for live-fire exercises was open from 9.30am and Adml Johnston labelled the noticed provided by the Chinese military as inadequate.
"The conduct of their activities was clearly disruptive," he said.
"It doesn't demonstrate the best practice that we would expect from mariners operating in that region, so it sure falls short of the standard that we apply to ourselves. And in that sense, it was irresponsible."
The alert from the NZ military came about 11am, he told the hearing, and confirmed there was no notification from the Chinese military or government before further drills on Saturday.
The People's Liberation Army-Navy is 250km south of Hobart and appears to be moving west.
Liberal senator James Paterson said "it's not really a notification for an upcoming exercise if we only find out about it after it's commenced".
The hearing was told militaries tended to notify authorities of planned exercises about 24 to 48 hours in advance.
Senator Paterson asked the defence chief if the three Chinese warships were likely to be getting support from a submarine.
"I don't know whether there is a submarine with them. Task groups occasionally do deploy with submarines but not always," Adml Johnston said.
He said the Australian military did not conduct firings near civil aircraft or civil maritime routes.
Defence secretary Greg Moriarty said he thought the Chinese were "signalling".
"They are practising and rehearsing and they are collecting," he said.
Forty-nine flights had to be diverted on Friday because of the Chinese navy's broadcast it was undertaking hazardous activity.
New Zealand Deputy Prime Minister Winston Peters raised the presence of Beijing's warships in the Tasman Sea with Chinese Vice President Han Zheng in a meeting on Wednesday.
Defence officials were also grilled on the chronology of communication with the government, after a Chinese fighter jet fired flares in front of a RAAF surveillance plane flying over the South China Sea.
Representing Defence Minister Richard Marles, Labor senator Jenny McAllister said the government had expressed its concerns through all official channels, in comparison to the "public chest beating" preferred by the former coalition government.
Adml Johnston said he was part of a briefing with Mr Marles on February 13.
Prime Minister Anthony Albanese said the government was conscious of the presence of Chinese ships and the Australian and New Zealand militaries were observing the group.
Opposition Leader Peter Dutton said "significant questions" remained over when the defence minister had been briefed.
