China challenged Australian warships in South China Sea, reports say

Royal Australian Navy frigate HMAS Toowoomba docked at Saigon port in Ho Chi Minh City, Vietnam, on April 19.

(CNN)Prime Minister Malcolm Turnbull asserted the right of the Australian navy to travel the South China Sea, after local media reported three Australian warships were challenged by the Chinese navy earlier this month.

As the three vessels traversed the hotly contested waters on their way to Vietnam, they were confronted by the People's Liberation Army (PLA) navy, the Australian Broadcasting Corporation reported on Friday.
The ABC said that one Australian defense official, speaking on condition of anonymity, "insists the exchanges with the Chinese were polite, but 'robust'."
    Prime Minister Malcolm Turnbull, in London for a meeting of the heads of Commonwealth nations, refused to confirm or deny the report.
    "All I can say to you is that Australia asserts and practices its right to freedom of navigation throughout the world's ocean, including the South China Sea," he told reporters.
    China's Defense Ministry confirmed the incident took place in a statement Friday but denied the version of events reported in the Australian media.
    "On April 15, Chinese naval ships encountered Australian warships in the South China Sea," the statement said. "When communicating with the Australian ships, the Chinese ships used professional language, and their operations were professional and safe in accordance with law and regulations."
    In a statement to CNN, the Australian Defense Department acknowledged the three vessels were in the South China Sea in recent weeks but wouldn't comment on "operational details" on the ships.
    "The Australian Defense Force has maintained a robust program of international engagement with countries in and around the South China Sea for decades," the statement said.
    The Australian ships are now conducting a three-day goodwill visit in Ho Chi Minh City in Vietnam.
    While Australian air force jets have been challenged by the Chinese in the past, this was the first time, Carl Thayer told CNN, that he'd heard of any reports of navy vessels being confronted.
    "That doesn't mean it hasn't occurred ... (But) the challenge is political, it's intimidatory and if you don't counter challenge then China can make the argument that the international community has acceded to China's claims," said Thayer, regional security analyst and emeritus professor at the University of New South Wales.

    Australia, China relations in deep chill

    The reported confrontation comes at a moment of frosty relations between Beijing and Canberra. Turnbull admitted to the diplomatic chill on April 12.
    "There has been a degree of tension in the relationship which has arisen because of criticism in China of our foreign interference laws," he told local radio station 3AW at the time.
    His remarks followed reports in local media that Australian ministers had been denied visas that would have allowed them to attend China's signature Boao Forum in Hainan province.
    The Chinese gov