Australia has raised the stakes in its already troubled relationship with China by backing the United States in formally declaring Beijing's territorial claims in the South China Sea to be illegal.
It comes after the United States this month rejected China's claims to offshore resources in most of the South China Sea.
In a letter to the United Nations, Australia's permanent mission rejected the Chinese Communist Party's claim to disputed islands in the crucial trading waters, calling them "inconsistent" with international law.
"The Australian Government rejects any claims by China that are inconsistent with the 1982 United Nations Convention on the Law of the Sea (UNCLOS), in particular, maritime claims that do not adhere to its rules on baselines, maritime zones and classification of features," the document states.
"There is no legal basis for China to draw straight baselines connecting the outermost points of maritime features or 'island groups' in the South China Sea, including around the 'Four Sha' or 'continental' or 'outlying' archipelagos.
On the same week it emerged that Australian warships had encountered the Chinese military near the disputed Spratly Islands, the federal government has joined the U.S. in formally rejecting China’s expansive maritime claims in the South China Sea at the United Nations pic.twitter.com/ByCYwYFFZj— Andrew Greene (@AndrewBGreene) July 24, 2020
"Australia rejects any claims to internal waters, territorial sea, exclusive economic zone and continental shelf based on such straight baselines."
The move, likely to infuriate Beijing, aligns Australia with the Trump administration, which earlier this month reversed a previous policy of not taking sides in such disputes.
Australia has previously urged all claimants to disputed South China Sea islands and maritime features to resolve their claims in accordance with international law.
China is yet to formally respond to Australia's statement.
But it said earlier this month that the US position "neglected the history and facts" around issues concerning the South China Sea.
Australia's dramatic shift in position comes as Foreign Affairs Minister Marise Payne and Defence Minister Linda Reynolds prepare to travel to Washington next week to meet with their US counterparts for the 2020 Australia-United States Ministerial Consultations (AUSMIN).
This week, the ABC revealed Australian warships had recently encountered Chinese warships while travelling through the South China Sea near the disputed Spratly islands, which Beijing claims.
Opposition Leader Anthony Albanese today backed the Morrison Government's hardening position on the South China Sea.
"Australia needs to defend the Australian national interest, and we also need to stand up for international law," Mr Albanese told reporters.
"And the international law of the sea provides for freedom of navigation, which is absolutely critical to international trade."