The Australian military only learnt Chinese warships were holding live-fire drills in the Tasman Sea 30 minutes after they began when they were alerted by civil aviation officials.

Australian Defence Force Chief Admiral David Johnston has also revealed the New Zealand military which was monitoring the three Chinese vessels waited a further hour to inform the ADF about the exercises.

Airservices Australia revealed on Monday that a Virgin Airlines pilot was the first to spot three Chinese warships off Australia’s east coast late last week.

Johnston told a Senate estimates hearing today the ADF received no direct warning of the exercise from the Chinese armed forces, and only heard of the drills after being told by civilian aviation officials on Friday morning.

Johnston said the Chinese had provided “inadequate notification” of the live-fire exercise.

His comment prompted a swift response by Liberal Senator James Paterson who said the Chinese navy had given “no notification at all”.

Patterson also questioned the length of time it took the New Zealand military to inform their Australian counterparts, saying he would have expected “direct and immediate” communication.

Johnston also gave an update on the position of the Chinese flotilla, comprising a frigate, a missile cruiser and replenishment vessel.

They are currently 250km south of Hobart, inside Australia’s exclusive economic zone, sailing south-west, and appear to be heading through the Great Australian Bight.

Johnston said the presence of an undetected nuclear submarine accompanying the surface ships could not be dismissed.

“I don’t know whether there is a submarine with them. It is possible: task groups occasionally do deploy with submarines, but not always,” he said.

“I can’t be definitive on whether that’s the case.” 

Prime Minister Anthony Albanese today said the government would be commenting further about the Chinese ships.

“Defence will make more comments about this today, but we have been conscious about the presence of Chinese ships … that’s why we had monitoring between Australia and New Zealand,” he said.

“The New Zealand vessel, of course, was tailing the task group as well so they were conscious and notified defence as well.”