TAIPEI (Reuters) - Taiwan President Ma Ying-jeou's planned trip to the Taiwanese-held island of Itu Aba in the disputed South China Sea is "extremely unhelpful" and won't do anything to resolve disputes over the waterway, a U.S. official said on Wednesday.
Ma's office earlier announced that the president, who steps down in May, would fly to Itu Aba on Thursday to offer Chinese New Year wishes to residents on the island, mainly Taiwanese coastguard personnel and environmental scholars.
But Ma's one-day visit to Itu Aba, known as Taiping in Taiwan, comes amid growing international concern over rising tensions in the waterway and quickly drew the ire of the American Institute in Taiwan (AIT), the de facto U.S. embassy in Taipei in the absence of formal diplomatic ties.
"We are disappointed that President Ma Ying-jeou plans to travel to Taiping Island," AIT spokeswoman Sonia Urbom said in an email to Reuters.
"Such an action is extremely unhelpful and does not contribute to the peaceful resolution of disputes in the South China Sea."
The United States wanted Taiwan and all claimants to lower tensions, rather than taking actions that could raise them, Urbom added.
On a visit to Beijing on Wednesday, U.S. Secretary of State John Kerry said Washington and Beijing needed to find a way to ease tensions in the South China Sea, through which $5 trillion in ship-borne trade passes every year.
"We talked about the possibility of a diplomatic way forward and Foreign Minister Wang Yi accepted the idea that it would be worth exploring whether or not there was a way to reduce the tensions and solve some of the challenges through diplomacy," Kerry said.
Both Taiwan and China claim most of the South China Sea. Vietnam, the Philippines, Malaysia and Brunei also have competing claims. Vietnam's most senior official in Taiwan said Hanoi "resolutely opposes" Ma's planned visit.
Itu Aba lies in the Spratly archipelago, where China's rapid construction of seven man-made islands has drawn alarm across parts of Asia and been heavily criticized by Washington.
Taiwan has just finished a $100 million port upgrade and built a new lighthouse on Itu Aba, which has its own airstrip, a hospital and fresh water.
Ma's visit follows elections won by the independence-leaning Democratic Progressive Party (DPP). Ma's office said it had asked DPP leader Tsai Ing-wen to send a representative, but the party said it had no plans to do so.
Beijing, recognized by most of the world as the head of "one China", deems Taiwan a wayward province to be retaken by force if necessary.
Yann-huei Song, a prominent Taiwan scholar who advises the government on South China Sea issues, said Ma was making the trip to make sure Taiwan, recognized by only a handful of countries, had a voice.
"No one is listening to Taiwan," Song, who is a research fellow with the prestigious Academia Sinica in Taiwan, told Reuters. "You are not allowed to participate in the multilateral dispute mechanism. What would you do?"
Ian Storey, a South China Sea expert at Singapore's ISEAS Yusof Ishak Institute, said he expected the Philippines and Vietnam to lodge a strong protest.
"But I do think it is unlikely they would stage a similar visit involving a senior political figure going to one of their own occupied islands ... that would risk inflaming relations with China and neither want to go that far," Storey said.
Asked to comment on Ma's planned visit, the mainland's Taiwan Affairs Office reiterated that China and Taiwan had a common duty to protect Chinese sovereignty in the waterway.
"Safeguarding national sovereignty and territorial integrity as well as safeguarding the overall interests of the Chinese nation is the common responsibility and obligation of compatriots across the straits," spokesman Ma Xiaoguang told reporters in Beijing.
The claims of both China and Taiwan are based on maps from the late 1940s belonging to the Nationalists, when they ruled all of China. The Nationalists fled to Taiwan in 1949 after losing the Chinese civil war to Mao Zedong's Communists.
But it has appeared unfazed 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.
Dustin Wang, a long-time Taiwanese scholar on the South China Sea who has visited Itu Aba, said one of Ma's goals was to highlight the island's civilian uses.
"Ma will demonstrate that facilities on the island, like the hospital, provide humanitarian assistance and disaster relief," he said.
Itu Aba was now the fourth largest island in the Spratlys after China's land reclamation work on Mischief Reef, Fiery Cross Reef and Subi Reef, Taiwan's coastguard said in October.
The island supports around 180 people, about 150 of them coastguard personnel who have had oversight of the 46-hectare (114-acre) island since 2000.
Additional reporting by Michael Martina and David Brunnstrom in Beijing, Sui-Lee Wee in Singapore and Greg Torode in Hong Kong; Writing by Dean Yates; Editing by Nick Macfie