Australia has raised concerns with China over what it said on Thursday were "unsafe and unprofessional" actions by a Chinese fighter jet towards an Australian maritime patrol in the South China Sea two days earlier, an account disputed by Beijing.

A Royal Australian Air Force (RAAF) P-8A Poseidon maritime patrol aircraft was conducting a routine surveillance patrol in international waters in the South China Sea on Tuesday when a Chinese PLA J-16 fighter jet released flares within 30 metres (100 feet) of the RAAF aircraft, Australia's Defence Minister Richard Marles said.

"That is an action that we've declared as being unsafe. We have made representations about our concerns to the Chinese government both yesterday and today here in Canberra, but also in Beijing," Marles said in a television interview with Sky News Australia.

The Chinese foreign ministry, in turn, accused the Australian aircraft of "deliberately intruding" into its airspace and "jeopardising" its national security.

"The expulsion measures taken by the Chinese side are legitimate, professional and restrained, and China has lodged solemn representations with the Australian side," ministry spokesperson Guo Jiakun told a press conference on Thursday.

China claims vast swathes of the South China Sea, despite overlapping claims by Brunei, Indonesia, Malaysia, the Philippines and Vietnam. China rejects a 2016 ruling by the Permanent Court of Arbitration in the Hague that its sweeping claims were not supported by international law.

A series of navy and air force interactions in the South China Sea that Australia has labelled as dangerous have previously strained diplomatic ties.

Australia's defence department also said that a Chinese navy task group was operating in Australia's north.

A People's Liberation Army Navy frigate, cruiser and replenishment vessel had entered Australia's maritime approaches, with the Jiangkai-class frigate Hengyang transiting the waters to Australia's north, the Defence Department said in a separate statement on Thursday.

Australia's air force and navy were monitoring the Chinese frigate, which had transited the Torres Strait between Australia and Papua New Guinea, and remained in Australia's exclusive economic zone, Marles said.

"I think the Australian people want to know that we've got a close eye on what this task group is doing... But from the perspective of international law, we will absolutely make sure that the way in which we go about this is both professional and safe," Marles said.

The Defence Department said in a statement Australia respects the rights of all states to exercise freedom of navigation and overflight and expected others to respect Australia's right to do the same.

https://www.amazon.com/Africircle-AfriPrime/dp/B0D2M3F2JT