Pope Francis has told Catholics in China to be “good Christians and good citizens”, reaching out to Beijing during his visit to neighbouring Mongolia.

Relations between the Vatican and Beijing, which have not had official diplomatic relations for more than 70 years, have been tense over the governance of China’s Catholics despite an agreement on the issue in 2018.

Following a mass in Mongolia’s capital of Ulaanbaatar on Sunday, Francis turned his attention to officially-atheist China, some of whose citizens had flown in for the papal visit.

Flanked by the Hong Kong bishop, Stephen Chow, and its bishop emeritus, Cardinal John Tong Hon, the 86-year-old pope said they joined him to send “a warm greeting to the noble Chinese people”.

Chow visited Beijing in April – the first visit by a Hong Kong bishop in more than 30 years.

“To the people, I wish the best,” said the pope. “To Chinese Catholics, I ask you to be good Christians and good citizens.”

In the crowd at the mass was a Chinese woman who had travelled to Mongolia from China’s northwestern city of Xi’an.

She said it had been “rather difficult to come”, revealing that the two organisers of her group’s pilgrimage had been detained back in China.

“Let me tell you, I feel so ashamed to hold the [Chinese] national flag,” she said.

“But I need to hold it and let the Pope know how difficult it is for us.”

The pope supported by ardinal John Tong Hon and Hong Kong's Archbishop Stephen Chow. He is wearing green robes and a white mitre with gold trimmings. speaking into a microphone

Pope Francis supported by Cardinal John Tong Hon and Hong Kong’s Archbishop Stephen Chow during the mass in Ulaanbaatar [Carlos Garcia Rawlins/Reuters]

There are only about 1,450 Catholics in Mongolia and the mass led by the pope in the capital involved almost the entire community.

There are an estimated 10 to 12 million Catholics in China, which has continued to appoint bishops without the Vatican’s approval as part of a “Sinicisation” campaign designed to ensure obedience only to the ruling Communist Party. In April, Beijing appointed a new bishop for Shanghai, the country’s biggest diocese.

Another Chinese woman at the mass in Mongolia said she felt “so blessed” to have attended the service and seen the pope.

“To have our own religion doesn’t mean that we are against our country,” the woman, from the province of Hebei, told the AFP news agency. “We actually pray for our country.”

The phrase used by the pope on Sunday – “good Christians and good citizens” – is one the Vatican uses frequently in trying to convince communist governments that giving Catholics more freedom would only help their countries’ social and economic progression.

The Vatican has used the same phrase about Vietnam, which in July upgraded relations by allowing the Vatican to have a resident papal representative in Hanoi.

The Vatican has asked China to allow a similar office in Beijing.

Chow, who will be made a cardinal by the pope this month, told reporters at a papal event on Saturday that he hoped the church in Hong Kong could be a “bridge” with mainland China.

Calling himself a “pilgrim of friendship”, Pope Francis extolled Mongolia’s virtues during his visit but warned of the dangers of corruption and environmental degradation, two major challenges faced by the nation.

The capital suffers from some of the world’s worst air quality and an embezzlement scandal sparked mass street protests last year.

Vast swathes of the country are also at risk of desertification due to climate change, overgrazing and mining.

The pope will leave Mongolia later on Monday.