The Chinese ship remained outside Australian territorial waters but was inside the Australian Exclusive Economic Zone in the Coral Sea, the ADF's statement said.
"The vessel's presence has not detracted from the exercise's objectives," Reuters quoted the ADF as saying.
The biennial joint military exercise Talisman Sabre involves more than 30,000 defense personnel from the three countries, which will end in late July, Reuters reported.
"Calling China's navy vessel a 'spy' ship to monitor military drills is an exaggeration, claim since the sailing of the Chinese ship inside the Australian Exclusive Economic Zone is consistent with international law," Li Jie, a Beijing-based naval expert, told the Global Times on Sunday.
This was not the first time that Western media speculated about Chinese naval ships. On July 14, CNN quoted US officials as saying that a Chinese "spy" ship had sailed in international waters off the coast of Alaska to observe the Terminal High Altitude Area Defense missile defense system test.
"Western countries like the US are trying to hype the 'China threat' theory and continue its rebalance to the Asia-Pacific region," Li said, adding that China's normal operations will not be obstructed.
This article was written by Zhang Hui and published in the Global Times.