Taiwan's outgoing chief executive has ignored criticisms from key ally the United States and departed for a disputed island in the South China Sea Thursday morning.

Taiwan's President Ma Ying-jeou, accompanied by about 30 members of his staff, left Taipei aboard a C-130 cargo airplane plane headed for Taiping Island, also known as Itu Aba.

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Taiping lies among the Spratly Islands, where Taiwan has overlapping claims with China, Vietnam, Malaysia and the Philippines. 

Ma's destination is the largest natural island in the area, but it is smaller in size to the artificial islands built by China out of reefs and shoals in the contested waters.

Shared Responsibility

The US, Vietnam and the Philippines have criticized Ma's trip, which Washington has said could heighten tensions in the region.  

"We remind all parties concerned of our shared responsibility to refrain from actions that can increase tensions in the South China Sea," Charles Jose, a spokesman from the Philippine Department of Foreign Affairs, said when asked by ABC News Australia to comment on Ma's visit.  

Taiwan has stationed about 200 coast guard personnel, scientists and medical workers on the disputed island, where the government maintains an airport. Taipei has government personnel scattered in other island groups in the disputed waters, including the Pratas Islands, which lies to the north of Taiping.

Ma -- who cultivated closer ties with China during his presidency -- is coming to the end of his eight-year term as Taiwan's leader, and has said that his trip is a demonstration of Taiwan's sovereignty over the territory. 

Rising Tensions

Tensions in the South China Sea have approached boiling point over the past few months even as China completes work on seven artificial islands in the region. 

The US has argued that the islands do not fall under claims of sovereign territory,  and sent a guided missile cruiser, the USS Lassen, within 12 nautical miles of Subi Reef, the site of one of China's maritime constructions, in October last year.

The move drew strong criticism from Beijing, who described the US action as "a coercive action that seeks to militarize the South China Sea region."

Ma's trip comes barely two weeks after his Nationalist Party was soundly defeated by the Democratic Progressive Party (DPP) led by Taiwan's president-elect Tsai Ing-wen, who is said to have refused the outgoing chief executive's invitation to join the trip.

China sees Taiwan as a breakaway province that will eventually be reunited with the mainland -- by force, if necessary. 

TagsChina-Taiwan relations, Ma Ying-jeou, Territorial disputes in the South China Sea