Defence Minister Judith Collins says she's aware of suggestions the Chinese navy ships in the Tasman Sea might be accompanied by a nuclear submarine.
Australian Defence officials have not ruled out that a nuclear-powered submarine might be with the three vessels and could be gathering intelligence.
"I am aware of suggestions that this task group has been accompanied by a nuclear submarine," Collins told RNZ in a statement.
"While Chinese task groups do occasionally deploy with submarines, I am not aware of any reports indicating that this is the case for this particular task group."
She had previously said the weapons the ships have "are extremely capable".
Sailors onboard the Royal Australian Navy ship HMAS Arunta looking at China's Fuchi-class replenishment vessel and Weishanhu Jiangkai-class frigate Hengyang in the Tasman Sea
The New Zealand spy agencies referred RNZ's queries - such as if they were liaising with Australian authorities about this - to Collins, who is also the minister for the GCSB and SIS. She did not comment on that.
The three Chinese navy ships were west of Tasmania on Thursday morning, heading west and entering the Great Australian Bight, the New Zealand Defence Force said.
The NZDF was working with the Australian Defence Force to monitor the ships, with the Anzac class frigate Te Kaha, maritime sustainment vessel HMNZS Aotearoa and P8-A Poseidon flights.
China said on Sunday that Australia's accusations over the ships not giving notice about live-fire drills had been hyped up.
"We are astonished," a spokesperson said.
Foreign Minister Winston Peters said on Thursday after a meeting with his Chinese counterpart in Beijing, that lack of a sufficient warning from China about the live-fire exercises was a "failure" in the New Zealand-China relationship.
