Pope Francis offered his support to Catholics in China on Wednesday, sharing at his weekly audience "a special thought to all those who suffer, pastors and the faithful".

Marking the World Day of Prayer for the Church in China -- an event instituted by pope Benedict XVI in 2007 -- Francis said he wished to emphasise his closeness with "our brothers and sisters in China, sharing their joys and hopes".

Speaking at the Vatican, the 86-year-old pontiff continued: "I address a special thought to all those who suffer, pastors and the faithful, so that they may experience consolation and encouragement in the communion and solidarity of the universal Church."

China's Communist Party is officially atheist and exercises strict control over all recognized religious institutions, including vetting sermons.

Francis led a years-long effort to build ties with Beijing and in 2018 the Holy See reached a two-year agreement on the thorny issue of the appointment of bishops.

The accord was renewed for two years in October, against a backdrop of tensions over the place of the country's estimated 10 million or so Catholics.

But at the end of November, the Vatican expressed "surprise" and "regret" at the appointment of a bishop in a diocese in China not recognised by the Holy

See, which violated the accord.

The deal, the contents of which have not been made public, aims to reunite Chinese Catholics split between the official and underground churches, while giving the pope the final say in appointing bishops.