A high-tech Chinese research vessel has been detected mapping strategically important waters off the Western Australian coast where submarines are known to regularly transit.

Key points: A Defence official said the ship was mapping waters used by Australian submarines to get to the South China Sea

A Defence official said the ship was mapping waters used by Australian submarines to get to the South China Sea A Border Force spokesperson said the Xiang Yang Hong 01 had stayed in international waters

A Border Force spokesperson said the Xiang Yang Hong 01 had stayed in international waters In 2018, the Xiang Yang Hong 01 was found to be operating illegally within the Exclusive Economic Zone of Palau

In January and February, officials closely tracked the movements of the oceanographic ship as it conducted deepwater surveys in the Indian Ocean near Christmas Island and the Australian mainland.

An Australian Border Force (ABF) spokesperson told the ABC it was aware of the Chinese vessel's presence and confirmed it had stayed within international waters.

"The Department of Home Affairs and the Department of Defence are aware that the Chinese oceanographic ship Xiang Yang Hong 01 [is off] the coast of Western Australia," the spokesperson said.

"The vessel has not entered the Australian Exclusive Economic Zone (AEEZ) other than for a direct transit through the AEEZ when transiting past Christmas Island."

One Defence official, speaking on the condition of anonymity, said the Xiang Yang Hong 01 was "undoubtedly" mapping waters regularly used by Australian submarines heading to and from the strategically important South China Sea.

"Beijing is keen to know as much as it can about the water, about these submarine routes, and it would also be wanting to test and monitor the Australian response to the presence of a high-tech Chinese vessel that's loitering off its coast," the official told the ABC.

The official also noted the Chinese vessel spent a considerable amount of time in waters not far from Naval Communication Station Harold E Holt, located just north of the town of Exmouth.

At the same time the Xiang Yang Hong 01 was detected off Western Australia's coast, the Virginia-class fast-attack submarine USS Texas arrived at HMAS Stirling naval base outside Perth, for a scheduled port visit.

According to the US Naval War College, the Xiang Yang Hong 01 was commissioned in 2016 for, among other things, "comprehensive observation in the field of military oceanography".

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In 2018, the Xiang Yang Hong 01 was found to be operating illegally within the Exclusive Economic Zone of Palau, prompting the tiny western Pacific nation to demand China remove the research vessel.

Last year, the ABC revealed two other high-tech Chinese ships were mapping waters close to Papua New Guinea where the United States and Australia had just begun upgrading a naval base on Manus Island.

The deepwater Chinese scientific surveys are part of Beijing's unprecedented oceanographic research of the Western Pacific, in an area experts believe could be crucial in any future maritime conflict with the US.

At the time, China's Foreign Ministry insisted its rapidly expanding oceanographic mapping activities were all conducted within international law and helping global scientific understanding.

"China's oceanographic, scientific research in the Western Pacific is totally in line with the United Nations Convention on the Law of the Sea and made contributions to maritime scientific study," Foreign Ministry spokesman Lu Kang told the ABC in April.