TAIPEI - Taiwan said on Tuesday (July 12) that it will never accept a ruling by a UN-backed arbitral tribunal that Taiping island and other features in the Spratly archipelago are "rocks" that are not entitled to a 200-nautical mile exclusive economic zone.

Its navy also said it will deploy another coast guard vessel on Wednesday to Taiwan-controlled Taiping - also known as Itu Aba - to patrol its surrounding waters. The navy had deployed a 2,000-tonne coast guard vessel on Sunday to the island.

The Philippines had brought the case to the Permanent Court of Arbitration (PCA) at The Hague against China's claims in the South China Sea. Although Taiwan is not a party to the case, its claims in the disputed waters are similar to those of China, and Taiping island was brought up in testimony during the court hearings.

"We will never accept it (the tribunal's ruling)... it is not legally binding. We will definitely defend our territorial sovereignty and not allow our... interests be harmed," said presidential office spokesman Alex Huang.

He said the arbitral tribunal did not formally invite Taiwan to participate in the proceedings, and "has never sought our advice".

South China Sea disputes should be resolved through multilateral negotiations, he said.

"We would also like, on the basis of equal consultation with relevant countries, to jointly promote peace and stability in the South China Sea," he added.

Previous Kuomintang (KMT) president Ma Ying-jeou had led a high-profile drive to present Taiping Island as an “island” which is entitled to a 200 nautical mile exclusive economic zone.

The KMT, now Taiwan’s biggest opposition party, said on Tuesday that it was “not satisfied” with the ruling, calling it “a serious violation of the sovereignty and interests" of Taiwan.

In a landmark ruling on Tuesday (July 12), the tribunal also concluded that China has no legal basis to claim "historic rights" to resources in the South China Sea and it has violated the Philippines' sovereign rights in the disputed waters.

China's nine-dash line map of the 1940s claims nearly the entire South China Sea. Its claims overlap those of four Asean states - the Philippines, Vietnam, Malaysia and Brunei - as well as Taiwan, in the potentially resource-rich South China Sea.

The sea is also a vital waterway through which some US$5 trillion (S$6.7 trillion) of ship-borne traffic passes each year.

Taiwan’s single holding of Taiping is the biggest feature in the Spratlys and the one that some analysts believe has the strongest claim to island status and an economic zone.

The Spratlys are also claimed by China, Vietnam and Malaysia, while Brunei claims nearby waters.