"China forcibly conducted large-scale rapid reclamation of maritime features which are being converted into military outposts," Japanese MP Akihisa Nagashima, a member of the ruling Liberal Democratic Party of Japan and ranking member of the National Security committee, told a meeting of Asia Pacific parliamentarians in Canberra on Tuesday.

China's actions were corrosive, and eroded trust, raised tensions and undermined peace and stability, he said, urging the other nations to back Japan's resolution.

"We should not sit on the sidelines in the face of these developments, if these kinds of actions are repeated, condoned and left unaddressed, they could completely subvert the existing regional order.

"We should reaffirm the very principal that any unilateral action by force or coercion to change the status quo is unacceptable."

China's actions were out of sync with hard-won international maritime law which did not allow the use of force or coercion, he said.

"I cannot over-emphasise the critical importance of the hard earned set of rules and principals for the stability and prosperity of the Asia Pacific."

Japan's call was notably forceful in a forum where many countries are talking in generalities about the need for regional cooperation. Russia, for example, spent a chunk of its time pushing for a renewed focus on cyber-security and talking up actions it is taking to prevent cyber attacks which it said it would share with the world as best practice.

A member of Japan's opposition, Hirano Honda, also sounded the alarm on China, over the South China Sea, and the ongoing protests in Hong Kong.

He said the United States withdrawal last year from its Intermediate-Range Nuclear Forces Treaty with Russia was "extremely regrettable".

"The stability of US China relationship is essential to the peace of the region," he said, urging the US, China and Russia to renegotiate a similar treaty.

The treaty, signed in 1987, banned intermediate range missiles. When it withdrew, the US said it had done so because Russia was not complying, but analysts were immediately reported as raising concerns that the collapse of the treaty could lead to a new arms race.

As the US looks for places in the region to deploy intermediate range missiles, Mr Honda told the Canberra forum allowing them in Japan or anywhere in the region risked an arms race with China.

China delegate Ding Zhongli said the world order had faced grave challenges in 2019, with growing instability, rising unilateralism and protectionism.

The region should work together to "firmly oppose unilateralism and bullying acts", he said.