China's state-backed Bishop of Beijing visited Hong Kong on Tuesday amid fears among some Catholics that Beijing wants tighter control over religious affairs in Hong Kong.

The visit is the first trip by a mainland Chinese bishop since the former British colony was returned to China in 1997 and follows a landmark visit to the Chinese capital by his Hong Kong counterpart in April.

For decades mainland Catholics have been split between an official church loyal to Beijing and an underground flock loyal to the Pope.

The visit of Bishop Joseph Li will be closely watched given lingering tensions between China and the Vatican.

Li did not answer questions from the media on Tuesday, but visited the Hong Kong Catholic Cathedral of the Immaculate Conception in the financial hub's Mid-Levels district, and was due to tour other church facilities and a seminary.

When asked by the media whether Li would meet officials from Hong Kong Liaison Office, Beijing's core representatives in the city, the Bishop of Hong Kong Stephen Chow said that "they were not an obstacle, but played an active role" because mainland China has their own standards and systems. 

Speaking to local media earlier this month ahead of the visit, Chow said Li's presence would serve to deepen connections between the Vatican and China.

Hong Kong has traditionally been seen as a regional Catholic hub on the edge of the Chinese mainland under officially-atheist Communist Party rule.

Beijing has been following a policy of "Sinicisation" of religion, trying to root out foreign influences and enforce obedience to the Communist Party. There are an estimated 10-12 million Catholics in China. Hong Kong has 600,000 Catholics.

Tensions between Beijing and the Vatican over the appointment of bishops saw a confidential pact struck in 2018. The pact has been renewed twice, but remains tenuous, with the Vatican complaining Beijing has broken it several times.

Cardinal Joseph Zen, 91, former Bishop of Hong Kong and one of the most prominent Catholic clerics in Asia, wrote in a blog ahead of the visit on Thursday night that even though the situation may be more difficult than before, people still have to persevere, stay calm, and hold their heads high. 

"Never consecrate a bishop without permission. Sacraments can be sacrificed, but faith cannot be sacrificed! Remember! Remember!" Cardinal Zen wrote.