Malcolm Turnbull, the Australian prime minister, asserted his country's rights to conduct patrols in the South China Sea after reports of a confrontation with China amid rising tensions in the disputed waters.

China's navy was said to have been involved in a "robust" but polite confrontation with three Australian warships in the strategically important sea, according to Australian Broadcasting Corp (ABC).

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, which is said to have taken place off the coast of Vietnam. But when prompted by reporters, he 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.