China denounced Japanese Prime Minister Shinzo Abe and US Defense Secretary Chuck Hagel on Sunday for "provocative" remarks accusing Beijing of destabilising actions in contested Asian waters.

Lieutenant General Wang Guanzhong, deputy chief of the general staff of the People's Liberation Army, told an Asian security forum in Singapore that strong comments made by Abe and Hagel at the conference were "unacceptable".

Abe had opened the Shangri-La Dialogue on Friday by urging countries to respect the rule of law -- an apparent reference to what rivals consider aggressive Chinese behaviour over disputed areas in the South China Sea and East China Sea.

Hagel on Saturday warned China against "destabilising actions" in the South China Sea and listed a number of alleged infractions, including against the Philippines and Vietnam, the two most vocal critics of Beijing's claims.

"The Chinese delegation... have this feeling that the speeches of Mr Abe and Mr Hagel are a provocative action against China," Wang, dressed in full military uniform, said in an address to the forum.

Abe had left Saturday and Hagel departed early Sunday before Wang spoke.

The Pentagon said Hagel and Wang held a brief meeting Saturday in which they "exchanged views about issues important to both the US and China, as well as to the region".

About midway into his prepared speech in which he said China "will never seek hegemony and foreign expansion", Wang diverted from the script.

He accused Abe and Hagel of "coordinating" with each other to attack China.

"This is simply unimaginable," said Wang, the highest ranking military official in the Chinese delegation, adding that the US and Japanese speeches were "unacceptable and not in the spirit of this Shangri-La Dialogue".

"The speeches made by Mr Abe and Mr Hagel gave me the impression that they coordinated with each other, they supported each other, they encouraged each other and they took the advantage of speaking first... and staged provocative actions and challenges against China," he said.

- 'Destabilising actions' -

Hagel issued a blunt message to Beijing on Saturday, saying "China has undertaken destabilising, unilateral actions asserting its claims in the South China Sea."

He accused China of restricting the Philippines' access to Scarborough Shoal, putting pressure on Manila's long-standing presence in Second Thomas Shoal, beginning land reclamation at various locations and moving an oil rig into disputed waters with Vietnam.

Hagel said that while Washington does not take sides on rival claims, "we firmly oppose any nation's use of intimidation, coercion, or the threat of force to assert these claims".

"The United States will not look the other way when fundamental principles of the international order are being challenged," he warned.

Abe in turn pledged that his country would play a larger role in promoting peace in Asia as his administration moves to reshape the Japanese military's purely defensive stance.

"Japan intends to play an even greater and more proactive role than it has until now in making peace in Asia and the world something more certain," Abe said.

Beijing and Tokyo contest islands in the East China Sea.

Wang, who stressed Beijing's historic rights to the seas, said he preferred Hagel's frankness by directly naming China, compared to Abe who did not mention any country but obviously targeted Beijing.

"If I am to compare the attitude of the two leaders, I would prefer the attitude of Mr Hagel. It is better to be more direct," he said.

As the conference drew to a close, French Defence Minister Jean-Yves Le Drian joined a chorus of senior defence officials urging rival claimants to show restraint to prevent larger conflicts.

Le Drian said a proposed agreement between China and the Association of Southeast Asian Nations (ASEAN) on a code of conduct to handle disputes in the South China Sea was "the only way to prevent incidents in that coveted area".

Singapore Defence Minister Ng Eng Hen urged Asian states not to "backslide into a fractious environment, riven by confrontational nationalism and lack of mutual trust".