Keyuan Zou, Harris professor of International Law at the University of Central Lancashire in the United Kingdom, said Article 298 of the UNCLOS gives the parties concerned the right to exclude some disputes from compulsory jurisdiction.

Zou said that since the case essentially concerns sovereignty and delimitation, "the Philippines used plenty of arguments, trying to convince the tribunal that the disputes they characterized are not excluded".

"Surprisingly, the tribunal has sided completely with the Philippines and explained the matter in a very loose and irresponsible way," Zou said.

This "created a very bad precedent, disrespecting the dignity of nation states and damaging the spirit of the rule of law", he said.

"If the official declarations made by nation states are so easily trumped by several individuals, the world legal order would become chaotic. One of the negative impacts could be that the United States is even more reluctant to join the UNCLOS." The United States has not ratified the UNCLOS.

A column published by the Philippine Star on July 10 said the arbitration "did look like an American ploy to internationalize the dispute".

It said that under the Aquino administration, the Philippines failed to devise an independent foreign policy and has been a subordinate "of the US in foreign-policy making".

In Beijing, the Foreign Ministry said on Monday that additional countries have announced their support for China's stance on the South China Sea.

Lu Kang, the ministry's spokesman, told a regular media briefing that countries such as Cambodia, Angola, Liberia, Madagascar, Papua New Guinea and Senegal made such announcements recently.

"More and more countries have voiced their position publicly despite pressure. That strongly proves that people have a sense of natural justice, while righteousness is widely supported," he said.