Hong Kong's Catholic bishop Michael Yeung

Michael Yeung, the Bishop of Hong Kong, said it would take time to address issues beyond the appointment of bishops agreed in the accord. These included the release of detained clerics and full free expression of religious belief in China.

The details of the provisional agreement, which gives the Vatican its long-desired approval of the appointment of bishops in China, have not been made public by either side.

Yeung, whose Hong Kong diocese has for decades served as a free Catholic beachhead on the edge of an officially atheist China, said he had not seen the details.

“I don’t think the signing of this provisional agreement means the solution of everything. It takes time, it will take a few years to see,” he told Reuters in a rare interview.

“A provisional agreement could not stop the suppression, could not stop the churches being torn down and the young folks under 18 still not allowed to go to church. These things will take time to solve,” he said.

China’s Foreign Ministry did not respond immediately to a faxed request for comment. The country is mostly closed for the Golden Week holiday.

Yeung urged China to provide information about priests and bishops detained on the mainland, some of whom are elderly and held for decades.

A Reuters report on Sunday cited three sources familiar with the matter who said the plight of the detained clergy remains unresolved and Beijing has provided little clear information about their fate.

Yeung said many Hong Kong Catholics had been praying for one of the longest held, Bishop James Su Zhimin, who was arrested in 1997 in Hebei province and would now be 86 years old.

“Whether he is in prison, or kept secret in some other place, or whether he has already died, nobody really knows,” he said.

Su was part of the underground church, which has been loyal to the Pope for decades - a movement that some critics of the accord fear will be crushed by the state-backed official church that has at times previously chosen its own bishops.

The deal allows for the Pope to approve bishops first selected by church communities and the Chinese authorities, meaning China’s 12 million Catholics split between the two camps must now effectively integrate.

Despite his concerns, Yeung said he supported the deal, saying that after years of trouble and talks it was vital to agree on something and move forward.

The soft-spoken Shanghai-born cleric, who took office in August last year, said he and his Hong Kong flock ultimately had to put their trust in God and the Pope.

Yeung said he had advised Pope Francis to strike a deal during an audience at the Vatican in August, but had also stressed the need for caution.

“I said...Holy Father, move forward, don’t be afraid but be cautious,” Yeung said.

“It is like crossing a river which you have never crossed before. You have to test the depth of the water, you have to touch the stones.”