BEIJING (Reuters) - International criticism of China over the disputed South China Sea will rebound like a coiled spring, a senior diplomat said on Friday (May 6), accusing the Philippines of ignoring treaties dating back to 1898 as it pushes its maritime claims.

China claims almost all of the energy-rich waters of the South China Sea, through which more than US$5 trillion (S$6.8 trillion) of maritime trade passes each year. The Philippines, Brunei, Vietnam, Malaysia and Taiwan have overlapping claims.

China's increasingly assertive moves in the waters, including building artificial islands and airports, have rattled nerves around the world, with the Group of Seven (G7) advanced economies warning last month they opposed provocation there.

G-7 leaders meet for a summit in Japan later this month.

Ouyang Yujing, Director-General of Chinese Foreign Ministry's Department of Boundary and Ocean Affairs, said he had noticed recent criticism of China coming from outside the region.

"Of course we're willing to take on board constructive comments and criticism by the relevant countries," Ouyang told a news briefing.

"But if they are aimed at putting pressure on China or blackening its name, then you can view it like a spring, which has an applied force and a counterforce. The more the pressure, the greater the reaction," he said.

China has been stepping up its rhetoric ahead of a ruling expected in a few weeks by the Permanent Court of Arbitration in The Hague on a case the Philippines has brought against China's claims in the South China Sea.

US officials have expressed concern the ruling could prompt China to declare an air defence identification zone, as it did over the East China Sea in 2013. China has neither confirmed nor denied it could do that.

The ruling is widely expected to favour the Philippines and risks significantly raising regional tensions because China rejects the court's authority to hear the case, even though it is a signatory of the UN Convention on the Law of the Sea under which it is being heard.

Ouyang said China had studied the Philippines' case and decided that it was ultimately about sovereignty and maritime delineation, and China was within its rights not to participate.

Three previous international treaties - in 1898, 1900 and 1930 - have already fixed the Philippines' boundaries, Ouyang said. According to those treaties, features such as the Spratlys and Scarborough Shoal are clearly Chinese, he said.

The Philippines began "illegally occupying" Chinese islands from the 1960s, Ouyang said.