US president Barack Obama has weighed in on territorial disputes in the South China Sea, urging regional powers, particularly China, to respect the law and stop "throwing elbows".

As several Asian regional powers face off over maritime borders, Mr Obama warned about disregard for existing laws and a move away from established ways of resolving disputes.

"If you start losing that approach and suddenly conflicts arise and claims are made based on how big the country is or how powerful its navy is instead of based on law, then I think Asia will be less prosperous and the Pacific region will be less prosperous," he said.

The United States does not hold any territorial claims in the South China Sea, Mr Obama added, but said that as a Pacific power Washington called on China and other nations to end reclamation.

His administration has vowed to continue sending military aircraft and ships to the tense region to protect navigation rights.

"We think that land reclamation, aggressive actions by any party in that area are counterproductive," Mr Obama said.

"China is going to be successful. It's big, it's powerful, its people are talented and they work hard, and it may be some of their claims are legitimate.

"But they shouldn't just try to establish that based on throwing elbows and pushing people out of the way."

China insists it has sovereignty over nearly all of the South China Sea, a major global shipping route believed to be home to oil and gas reserves, but rival claimants accuse it of expansionism.

The US has acknowledged that other claimants have developed outposts of differing scope and degree, including Vietnam with 48, the Philippines with eight, Malaysia with five and Taiwan one.

But it said China had reclaimed more than 2,000 acres, more than all other claimants combined and only the past 18 months.

China says its actions are peaceful and mostly aimed at fulfilling maritime, scientific and disaster prevention obligations.

AFP/Reuters