Pope Francis has voiced optimism for improved ties between the Vatican and China, rejecting criticism that the Holy See may be selling out Catholics to Beijing's communist government.

The Vatican and China are in advanced talks to resolve a dispute over the appointment of bishops in China, one of the biggest obstacles to resuming diplomatic ties that were cut almost 70 years ago.

"We are at a good point," the pope told Reuters in an interview at his Vatican residence.

China's estimated 12 million Catholics are split between an underground Church that swears loyalty to the Vatican and the state-supervised Catholic Patriotic Association.

Pope Francis did not comment in the interview on the details under discussion but said dialogue was the best way forward.

"Dialogue is a risk, but I prefer risk rather than the certain defeat that comes with not holding dialogue," he said.

"As for the timing, some people say it's 'Chinese time'. I say it's God's time. Let's move forward serenely."

Francis said the road to reconciliation with China was divided into three paths -- the official dialogue, unofficial contacts among ordinary citizens "which we do not want to burn," and cultural dialogue.

"I think the Chinese people merit the Nobel Prize for patience. They know how to wait. Time is theirs and they have centuries of culture .... They are a wise people, very wise. I have great respect for China," he said.

Asked about the comments, Chinese Foreign Ministry spokesman Geng Shuang said China was sincere about improving two-way ties with the Vatican, and had made "unremitting efforts".

"We are willing to meet the Vatican side halfway, and make new progress in the process of improving relations and advancing constructive bilateral dialogue," Geng told a regular news briefing in Beijing on Thursday, without elaborating.

The most outspoken critic of the pope's China strategy is 86-year-old Cardinal Joseph Zen, a former bishop of Hong Kong, who has said the direction of negotiations suggests the Vatican is preparing to sell out the underground church.

In Hong Kong, a beachhead for Vatican loyalists in southern China, some priests say the talks could be a trap leading to greater persecution of underground believers and ultimately to tighter Communist Party control of their religion.