TAIPEI (Reuters) - The incoming Taiwanese government on Sunday accused China of “political interference” after a senior Chinese official cast doubt over the island keeping its observer status at the World Health Organisation if bilateral relations deteriorated further.

Taiwanese President Ma Ying-Jeou (R) shakes hands with President-elect Tsai Ing-wen (L) after discussing the transfer of power in a meeting in Taipei, Taiwan March 30, 2016. REUTERS/Tyrone Siu

China and self-ruled Taiwan underwent a rapprochement under the outgoing government which was run by China-friendly Nationalists, but ties have begun to strain with their successors, the independence-leaning Tsai Ing-wen and her Democratic Progressive Party (DPP).

Tsai and the DPP won landslide presidential and parliamentary elections in January, in part on rising anti-China sentiment on the island. She has said she will maintain the status quo with China, but has never conceded to a key bilateral agreement, the “one China” principle.

Under this agreement with the Nationalists, Taiwan and China agree they are both part of a single China although both sides lay claim to being its legitimate government.

On Friday, Ma Xiaoguang, spokesman for the Taiwan Affairs Office, China’s top agency that deals with the island, said that Taiwan’s participation in the World Health Assembly was an arrangement based on the “one China” principle, and that this could cease “should the political foundation of cross-Strait ties be destabilized in the future,” according to a state-run Xinhua report.

Taiwan, an island separated by the Taiwan Strait from mainland China, has attended the annual gathering of the World Health Assembly, the decision-making body of the WHO, since 2009 in an observer status.

Incoming DPP cabinet spokesman Tung Chen-yuan said the comments by the Taiwan Affairs Office were unacceptable.

“We believe this is political interference in our participation in the WHO. We cannot accept this and express our solemn protest,” Tung said at a press conference late Sunday.

“Taiwan people’s health and their right to fully participate in the international community must not be constrained by any political framework,” he said.

China has considered self-ruled Taiwan a wayward province ever since defeated Nationalists fled to the island after a civil war with China’s Communists in 1949. Beijing has never renounced the use of force to take back the island, particularly if it makes moves toward independence.

Tung said Taiwan’s participation in the upcoming WHO meeting and the issue of “one China” were not associated matters, indicating the new government was not conceding to accepting the “one China” principle.

Taiwan has diplomatic ties with only 22, mostly small and poor, states. Most major nations and multilateral organizations, like the WHO which falls under the United Nations, formally recognize China.

The WHO invited Taiwan, but the invitation also referenced a resolution under the U.N. that recognizes China, according to the Taiwan government.

Tung said the incoming government will send its new health minister Lin Tzuo-yien to the meeting, which will be held in Geneva May 23-28.