TAIPEI (Reuters) - Taiwan’s vice president will next month visit the Vatican, its sole diplomatic ally in Europe, on a trip that could anger China as the Holy See looks for rapprochement with the world’s most populous country.

Chen Chien-jen will be the special envoy for Taiwan President Tsai Ing-wen, who the Vatican invited for a Sept. 4 ceremony to declare Mother Teresa a saint, the Taiwan government said on Wednesday.

Tsai leads the independence-leaning ruling Democratic Progressive Party in Taiwan, which Beijing distrusts. Chen is part of the DPP-led government but is not a party member.

The Vatican is the only Western state that does not have diplomatic ties with Beijing, maintaining instead formal relations with the Republic of China, based in Taiwan, which Beijing views as a renegade province.

The Vatican is one of Taiwan’s only 22 allies, most of which are small, poor countries. China says that as Taiwan is one of its provinces, the island has no right to diplomatic relations with anyone.

The visit comes as Pope Francis is leading a push to fundamentally alter the relationship between the Vatican and China, which for decades has been infused with mutual suspicion and acrimony.

For the Vatican, a thaw in relations with China offers the prospect of easing the plight of Christians who for decades have been persecuted by the authorities.

It may also ultimately pave the way to diplomatic relations, giving the Church full access to the world’s most populous nation.

Officials in Taipei played down the possibility of China taking away another ally after it this year established ties with Gambia, a former ally of Taiwan.

“The diplomatic friendship between the Republic of China and the Vatican has always been very solid. We have shared values with the Holy See, such as religious freedom and human rights,” Deputy Foreign Minister Wu Chih-chung told reporters.

Taiwan does not oppose exchanges between the Vatican and mainland China because it is the job of the Holy See to promote the Catholic faith, Wu said.

China’s Foreign Ministry did not immediately respond to a request for comment on Chen’s trip.