The federal government confirmed that a Chinese spy ship spent three weeks off the Australian coast in August and September.
The Yuhengxing, a general intelligence vessel, transited the Torres Strait and sailed to Sydney.
Prime Minister Scott Morrison said the ship was in waters off the Australian coast and not in territorial waters, adding that it was legally allowed to be there just as Australia is allowed to navigate through the South China Sea.
“We were keeping an eye on them just as they were watching us,” he told reporters on Friday.
A photo released by the Defense Ministry shows HMAS Supply monitoring the Chinese vessel.
Home Secretary Karen Andrews said Australia had been keeping a close watch on the ship as part of ongoing border protection issues.
Treasurer Josh Frydenberg reiterated that Australia has taken the necessary precautions and hailed the new AUKUS trilateral security agreement with the United States and Britain as vital to national security.
“No surprises here, everyone wants the opportunity to get that little bit of extra information if they can,” he told the Seven Network.
“We knew they were there, we continued to do our business … but it also underscores the difficult strategic environment in which Australia finds itself.
“We have entered into strategic partnerships like AUKUS with two valuable and trusted partners who will share the latest technology with our defense forces and with our security personnel.”
Mr Morrison said significant security concerns in the region warranted strong Australian action and reaffirmed the need for the government to acquire nuclear-powered submarines.
“Australia has to be able to stand up and that takes a lot of strength,” he said.
“The presence of the Chinese navy demonstrates to Australians that there is a very serious situation in the Indo-Pacific.
“No one can be complacent about the situation.”
China has already sent military ships to monitor defense training exercises, such as the Talisman Saber off the east coast in July, and three warships have sailed into Sydney Harbor unannounced to the eve of the anniversary of the Tiananmen Square massacre in 2019.
Associated Australian Press