KUALA LUMPUR (BLOOMBERG) - Malaysia has rejected China's expansive maritime claims in the South China Sea in a rare public rebuke of its largest trading partner.

The government made a submission to the United Nations two weeks ago on its rights over the remaining portion of a continental shelf beyond 200 nautical miles from the country's baselines, Foreign Minister Hishammuddin Hussein told Parliament on Thursday (Aug 13).

It was in response to a similar claim China made to the UN on Dec 12, he said.

"Malaysia opposes China's claim that they have historic rights over those waters," said Datuk Seri Hishammuddin. "The Malaysian government also considers China's claims over maritime features in the South China Sea to have no basis whatsoever under international law."

The rebuke is an unusual move for Malaysia, which had previously avoided reproaching China openly by reiterating its focus on ensuring the area remains open for trade.

Its submission to the UN comes on the heels of Australia and the US rejecting China's maritime claims in response to what the two allies see as an intensifying campaign to dominate the resource-rich area.

China has built bases and other outposts on shoals, reefs and rock outcroppings to deepen its claim over 80 per cent of the 3.6 sq km waterway, with Vietnam, the Philippines, Brunei, Malaysia and Taiwan claiming parts of the same area.

Malaysia will remain cautious in defending its claim to avoid escalating tensions, Mr Hishammuddin said. It will keep working toward a resolution within regional grouping Asean, which is holding discussions with China for a code of conduct for the area, even as talks have stalled due to the pandemic, he added.

"If we follow the narratives and pressure of superpowers, there's a high potential for Asean countries to lean toward certain countries," said Mr Hishammuddin.