Australian ships are currently conducting exercises with the US and Japanese navies. Australian warships have encountered the Chinese navy in the South China Sea during a voyage that saw them sail close to contested islands claimed by Beijing. The ships were en route to exercises with the US and Japan. The ADF says all unexpected encounters are handled professionally

Last year the Navy was closely followed by the Chinese military during a similar transit of the South China Sea

The ABC has learnt an Australian Defence Force joint task group consisting of five warships last week travelled through the disputed waterways, including close to the Spratly Islands, which China claims as its own.

It is understood the Australian warships did not come within 12 nautical miles of the contested islands, unlike American warships, which have recently conducted freedom of navigation exercises to challenge Beijing's territorial claims.

In a statement, Defence insisted all "unplanned interactions with foreign warships throughout the deployment were conducted in a safe and professional manner".

The Australian warships, led by HMAS Canberra, were transiting through the increasingly tense region as they made their way to the Philippine Sea for training exercises with the American and Japanese navies.

Soon HMAS Canberra, HMAS Hobart, HMAS Stuart, HMAS Arunta and HMAS Sirius will arrive in Hawaii for larger military war games known as RIMPAC.

A man in a navy uniform and life jacket stands beside a rocket launcher on a ship.

"Australia is committed to a secure, open, prosperous and resilient Indo-Pacific region. We routinely work with regional partners to address shared security challenges," a Defence spokesperson said.

"Activities conducted during this routine deployment are part of the Australian Defence Force's regular military-to-military engagements throughout the Indo-Pacific, which are conducted each year."

It is not known precisely where the Chinese military interacted with the Australian joint task group, but Defence confirmed the warships sailed near the disputed Spratly Islands last week.

Last year, the Royal Australian Navy was closely followed by the Chinese military during a similar transit of the South China Sea.

US Defence Secretary Mark Esper this week signalled the American military would conduct more freedom of navigation operations (FONOPS) to challenge Beijing's territorial claims in the South China Sea.

"In 2019 we conducted the greatest number of freedom of navigation operations in the South China Sea in the 40-year history of the FONOPS program, and we will keep up the pace this year," he said.