The Philippines on Monday reminded China of United Nation's arbitral tribunal ruling, stating that the artificial islands it built in the South China Sea are within the Philippines exclusive economic zone.

"What is ours is ours," Presidential spokesperson Harry Roque said in a media briefing in Malacanang in the wake of Chinese ongoing activities in the disputed waters, particularly in the three artificial islands, which are also being claimed by the Philippines.

"The arbitral tribunal is evidence that (they were) built on waters which form part of our EEZ and only the Philippines has sovereign rights to construct those islands," Roque said.

He reiterated that based on the arbitration ruling, China's historical and sovereign claim in almost the entire South China Sea through its nine-dash line has "no legal basis".

China reportedly installed military systems in the Philippine-claimed Panganiban, Zamora and Kagitingan reefs.

Roque insisted that the government is doing something about the issue but it could not publicly announce every move that it has been taking.

President Rodrigo Duterte has decided to be soft on China insofar as the South China Sea issue is concerned.

Roque said the Philippines is "quietly" working with other Southeast Asian countries, which have also claim in the South China Sea, for the peaceful resolution of the dispute. Aside from the Philippines and China, the other ASEAN countries, which have claim in the area are Brunei, Malaysia and Vietnam. Taiwan is also a claimant. Ella Dionisio/DMS