TAIPEI (Reuters) - Taiwan on Friday (May 13) called on an international tribunal not to make a ruling on a disputed South China Sea island if the judges don't visit first to see for themselves it can sustain life.

Taiwan wants to prove Itu Aba is not just a rock, but a real island that can qualify for a maritime economic zone.

China refuses to recognise a case lodged by the Philippines with the Permanent Court of Arbitration in The Hague over the South China Sea and says such disputes should be resolved through bilateral talks.

The panel does not rule on sovereignty but it does outline a system of economic zones that can be claimed from features such as islands.

"The government of the Republic of China (Taiwan's formal name) once again solemnly invites the five arbitrators (in the Philippine case) to conduct a field study on Taiping Island," Taiwan's foreign ministry said in a statement. "If the tribunal decides not to respond to our kind invitation, then it should not rule on the legal status of Taiping Island."

Last month, the panel allowed written evidence from a government-linked Taiwanese group pressing Taipei's position that Itu Aba is not a rock and is entitled to part of the disputed waterway as an economic zone.

China, which claims sovereignty over self-ruled Taiwan, also claims almost the entire South China Sea. Brunei, Malaysia, the Philippines, Taiwan and Vietnam also have claims to the waters.

Taiwan has just finished a US$100 million (S$137.1 million) port upgrade on Itu Aba, known as Taiping in Taiwan, in the disputed Spratly islands. The island has an airstrip, a hospital and fresh water.

Itu Aba is the biggest natural island in the Spratlys and is the only one claimed by Taiwan.

Manila is challenging the legality of China's claim, in part by arguing that no land mass in the Spratly archipelago can legally be considered a life-sustaining island, and therefore, cannot hold rights to a 370 km exclusive economic zone.

China has appeared unruffled by Taiwan's upgrading work on Itu Aba. Military strategists say that is because Itu Aba could fall into China's hands should it ever take over Taiwan.

China has claimed sovereignty over Taiwan since 1949, when Mao Zedong's forces won the Chinese civil war and Chiang Kai-shek's Nationalists fled to the island. Beijing has vowed to bring Taiwan under its rule, by force if necessary.