Chinese military 'challenged Australian warships in the South China Sea'

China's navy was involved in a "robust" confrontation with three Australian warships in the disputed South China Sea, media reported.

The exchange, which took place off the coast of Vietnam, prompted Prime Minister Malcolm Turnbull to assert Australia's rights to conduct patrols in the strategically important waters.

Australian Broadcasting Corp said the exchanges between the Chinese and the Australian militaries were polite but "robust".

The broadcaster, which first reported the incident, said it was "believed to have occurred earlier this month as China was conducting its largest ever naval exercises".

Mr Turnbull, who is in London on a visit, did not comment on the specific confrontation when asked by reporters, but said: "We maintain and practice the right of freedom of navigation and overflight throughout the world and, in this context, we'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."

Australian defence officials did not confirm the confrontation took place, but said three warships had arrived in Ho Chi Minh City on Thursday. They are making a three-day goodwill visit to Vietnam.

On the same day, Chinese President Xi Jinping presided over huge exercises in the South China Sea in an unmistakable show of force to Beijing's regional rivals.

The drills involved 48 ships, among them China's sole operating aircraft carrier, the Liaoning, along with 76 helicopters, fighter jets and bombers, and more than 10,000 personnel.

ABC said the HMAS Anzac, HMAS Toowoomba and HMAS Success were challenged by China's People's Liberation Army (PLA) Navy.

China claims almost all of the South China Sea, where more than $5 trillion (£3.8 trillion) of trade passes every year. 

Much of the sea is also claimed by several south-east Asian nations, including the Philippines, Brunei, Malaysia, and Vietnam.

Observers say China is developing its military capabilities by fortifying and building infrastructure on what were previously reefs and partially-submerged islets.

The US Navy has been confronting China in the region with 'freedom of navigation' exercises.

It sent the aircraft carriers Theodore Roosevelt and Carl Vinson through the South China Sea in recent months, angering Beijing.

Washington has also called on Australia to carry out similar patrols.