MELBOURNE (BLOOMBERG, REUTERS) - Australian leader Malcolm Turnbull has said his navy has a "perfect right" to conduct freedom of navigation exercises in the South China Sea after a media report said three of his frigates had been challenged by Chinese forces.
"We maintain and practice the right of freedom of navigation and overflight throughout the world," Prime Minister Turnbull told reporters in London on Thursday (April 19).
"In this context, you're talking about naval vessels on the world's oceans, including the South China Sea, as is our perfect right in accordance with international law."
The Australian warships were challenged by the Chinese military in the disputed South China Sea earlier this month, the Australian Broadcasting Corp reported, citing Australian defence officials.
The Australian Defence Department confirmed that three ships had recently travelled to Ho Chi Minh City in Vietnam, but declined to comment on "operational details related to ships transiting the South China Sea".
The People's Liberation Army, conducting its largest-ever naval exercises in the region earlier this month, challenged the frigates as they were transiting toward Vietnam for a goodwill visit, the Australian Broadcasting Corp reported, citing military sources it didn't identify.
The ABC cited one official saying the exchanges with the Chinese navy were polite but "robust".
"The Australian Defence Force has maintained a robust programme of international engagement with countries in and around the South China Sea for decades," the Defence Department said in a statement e-mailed to Reuters.
"This includes bilateral and multilateral military exercises, port visits, maritime surveillance operations and ship transits," the department told the ABC.
Defence Industry Minister Christopher Pyne downplayed the seriousness of the incident.
"I think 'confrontation' is somewhat of a tabloid-style description of what goes on in the South China Sea very regularly," he said, reported the ABC.
China's claims in the South China Sea are hotly disputed by Vietnam, as well as the Philippines, Malaysia, Brunei and Taiwan.
"As they have done for many decades, Australian vessels and aircraft will continue to exercise rights under international law to freedom of navigation and overflight, including in the South China Sea," the Australian Defence Department said.
China's construction of islands and military facilities in the South China Sea, through which some US$5 trillion (S$6.56 trillion) in trade passes annually, has sparked concerns Beijing is seeking to restrict free movement and extend its strategic reach.
The United States has conducted "freedom of navigation patrols" through the South China Sea, stoking tensions with China which says it will protect its sovereignty.
In response to those freedom of navigation operations, China's Foreign Ministry said it had dispatched military vessels and fighter planes to warn off the US vessels.
In 2015, a team of CNN journalists captured a warning issued by the Chinese military to a P8-A Poseidon, the US' most advanced surveillance aircraft, as it flew a mission over the Fiery Cross Reef.
"Foreign military aircraft. This is Chinese navy. You are approaching our military alert zone. Leave immediately," a Chinese naval officer warned.
A total of eight warnings were issued to the plane, ranging from a simple, "You go," to "This is the Chinese navy. This is the Chinese navy. Please go away quickly."
The Australian navy ships Anzac, Toowoomba and Success are on a three-month deployment in South East Asia, which will involve exercises with a number of countries in the region, the Defence Department said in a separate statement on April 17.
The Toowoomba sailed to Vietnam from Malaysia, while the other two Australian warships went through the South China Sea from Subic Bay in the Philippines.