Defence Minister Richard Marles could not say whether the Chinese flotilla off Australia is travelling with a nuclear submarine, adding that authorities are unsure whether any live firing even took place.

Three Chinese warships — a frigate, cruiser and replenishment ship — were conducting live-firing drills off Sydney in the Tasman Sea on Friday, which forced planes to divert mid-flight.

A Virgin Airlines pilot reported their presence in the international waters at 9.58am and Australia’s Defence Force was notified shortly after 10am.

New Zealand then notified Australia about an hour and a half later. 

Speaking to ABC Radio National Breakfast, Marles said Beijing’s notice to Canberra of the live firing was inadequate but could not say whether it actually took place.

“It’s also the case, though that it’s not clear on Friday whether any live firing took place,” he said.

“That’s to say the New Zealand frigate, which we were working closely with, which was the frigate that was observing the task group at the time, didn’t observe any live firing on that day.

“But we’re not suggesting here for a moment that what occurred was adequate.”

Marles defended how long it took Australia to be made aware of the Chinese vessels, adding that “it wasn’t a real incident”.

“To equate what is going on with the observation of a Chinese exercise with a real threat is not fair in terms of what is going on right now versus this is the kind response we would have if there is a real live threat,” he told ABC Radio.

“There is a task group which is undertaking an exercise and we are surveilling that exercise and that is a very different circumstance to the country being under threat.”

Australian authorities, including Prime Minister Anthony Albanese, have maintained that China is acting in accordance with international law.

Speaking to suggestions the flotilla is accompanied by a nuclear submarine, Marles said Australia does not know.

“We don’t know whether there is a presence of a submarine and that, in part, speaks to the nature of submarines,” he told ABC Radio.

The Chinese flotilla is currently about 500km west of Hobart and is teetering on the edge of Australia’s Exclusive Economic Zone.

According to the defence department, the ships entered our exclusive zone on Tuesday.