BEIJING/HONG KONG (Reuters) - China and the Vatican will establish formal diplomatic relations sooner or later because Pope Francis has the “wisdom” to resolve problems between the two sides, a state-run Chinese newspaper said on Tuesday, amid increasing controversy over the issue.

FILE PHOTO: Pope Francis leads a mass for priests and nuns in Saint Peter's Basilica at the Vatican February 2, 2018. REUTERS/Max Rossi

A framework accord between the Vatican and China on the appointment of bishops is ready and could be signed in a few months in what would be an historic breakthrough in relations, a senior Vatican source said last week.

But on Monday, Cardinal Joseph Zen, 86, the outspoken former bishop of Hong Kong said the Vatican is selling out China’s underground Catholics and “forcing them into a bird cage,” raising the ante in his recent criticisms which had already sparked a rebuke from the Vatican.

An even partial resolution of the thorny issue of who gets to appoint bishops could open the way for a resumption of diplomatic relations nearly 70 years after they were cut during the Communist takeover of China, when missionaries were expelled from the country.

Beijing later established the official Catholic Patriotic Association, which does not recognize the Pope, while “underground” Catholic communities that remain loyal to the Vatican have been systematically persecuted for decades.

China has so far said little about the talks.

However, the widely read tabloid the Global Times said a deal between Beijing and the Vatican would be “tremendously beneficial to Catholics”.

“Despite the difficult process, China’s vast numbers of non-Catholics have never been strongly against the Vatican. The Chinese public generally respects each Pope,” it said in an editorial in its Chinese and English-language editions.

“Beijing and the Vatican will establish diplomatic relations sooner or later ... Pope Francis has a positive image with the Chinese public. It is expected he will push China-Vatican ties forward and solve related problems with his wisdom,” it said.

The newspaper is published by the ruling Communist Party’s official People’s Daily but, unlike its sister publication, does not speak for the party or the government.

The moves have not been without controversy in the church.

“Our brothers in mainland China are not scared of losing all their fortunes, being thrown into jail or even bleeding. Their greatest pain is from being betrayed by their ‘family members,’” wrote Zen, who vowed to keep speaking out despite the Vatican’s rebukes.

He also said the Pope had, during a meeting with him three years ago, agreed that the official Catholic community run by the Chinese Communist Party objectively represents a schism.

Another source of friction with China is the Vatican’s maintenance of official ties with self-ruled Taiwan, which Beijing sees as a wayward province to be taken back by force if necessary.

“The Taiwan question isn’t Beijing’s top concern in handling its relations with the Vatican as the mainland has many tools to pressure Taiwan,” it said.

The Vatican is Taiwan’s sole remaining European diplomatic ally. China has been ramping up the pressure on Taiwan since Tsai Ing-wen of the pro-independence Democratic Progressive Party won presidential elections in 2016.