Australia and Indonesia voice 'serious concerns' about South China Sea

Australia and Indonesia have jointly declared "serious concerns" about the state of the South China Sea, issuing a warning about China's militarisation of the contested waters and urging adherence to international law.

The joint statement from the Australian and Indonesian governments – released following the annual meeting of the countries' defence and foreign ministers – underscores ongoing regional anxiety about the Chinese government's efforts to consolidate its claims in the disputed sea.

Australian and Indonesian ministers Linda Reynolds, Marise Payne, Retno Marsudi and Prabowo Subianto met in Denpasar on Friday. Credit: AP

"The ministers expressed serious concerns about developments in the South China Sea and reaffirmed the importance of maintaining peace, security and stability, and freedom of navigation and overflight in the region," the statement said.

It outlined "concern at the continued militarisation of disputed features" and called for claimants to avoid actions that risked escalating tensions.

The ministers also said a South China Sea code of conduct – the subject of years of discussions between China and the Association of south-east Asian Nations (ASEAN) – must be "substantive", consistent with international law and "not prejudice the interests of third parties".

China, which controversially claims a vast swathe of the South China Sea as its territory, reportedly does not want any code to be subject to the United Nations Convention on the Law of the Sea (UNCLOS) and wants to curb the United States' involvement in the region.

In 2016, an international tribunal established under UNCLOS ruled against China in a dispute with the Philippines over the two countries' claims. China has ignored the finding and pursued a program of land reclamation and militarisation of disputed features.

During their meeting in Denpasar on Friday, Australian ministers Marise Payne and Linda Reynolds, and Indonesian ministers Retno Marsudi and Prabowo Subianto discussed the regional dispute as one of their key issues.

The joint statement said ministers had noted Australia's and Indonesia's strategic outlooks were "converging" in an increasingly contested region.

"They emphasised our two countries' shared interest in an Indo-Pacific region that is open, inclusive and prosperous, and where countries adhere to international law and other agreed rules and norms," the statement read.

Ben Bland, director of the south-east Asia program at the Lowy Institute, said Indonesia, like other countries in the region, was "increasingly concerned by China's assertiveness" in the South China Sea.

A man-made Chinese airstrip in the heavily contested South China Sea.Credit: AP

"But it remains reluctant to upset Beijing and wants to be seen as an independent 'honest broker' rather than appearing to 'gang up' on China," he said.

While Indonesia is not a claimant in the South China Sea, the country's Natuna Islands sit at the southern edge of the waters claimed by China and the area has been a source of tension between Jakarta and Beijing.

The Indonesian and Australian ministers also discussed plans for joint deployment of peacekeepers to future conflict zones, with Senator Reynolds calling the development "very exciting".

Mr Bland said the meeting underlined a "steady maturation" of Australia-Indonesia relations.

"Both countries now need to capitalise on this by thickening economic, military and political ties, while developing more mutual understanding to deal with the inevitable hiccups that arise in neighbourly relations," he said.