The trial of Cardinal Joseph Zen on charges of sedition is underway in Hong Kong.
The 90-year-old cardinal is standing trial with five others over his involvement in the now defunct 612 Humanitarian Relief Fund, which provided legal and financial assistance to pro-democracy activists.
The trial had been due to start last week but was set back temporarily after the judge contracted Covid-19.
Cardinal Zen is standing trial alongside singer Denise Ho, former lawmakers Margaret Ng and Cyd Ho, university professor Hui Po-keung, and Sze Ching-wee, former secretary of the 612 Humanitarian Relief Fund.
The arrest of the former bishop of Hong Kong in May shocked the world.
Pope Francis has been accused of betraying the cardinal after refusing to criticise Beijing over his arrest and trial.
On the day of Cardinal Zen's arrest, the Vatican said only that it was following developments "with extreme attention".
Asked recently whether he thought that the trial of Cardinal Zen was a violation of religious freedom, the Pope said he was committed to dialogue with China.
"To understand China takes a century, and we do not live for a century," he said.
"In order to understand we have chosen the path of dialogue, open to dialogue.
"It is not easy to understand the Chinese mentality, but it should be respected, I always respect this.
"Understanding China is an enormous thing. But you do not have to lose patience, we have to go with dialogue."
Cardinal Zen joins a number of pro-democracy activists who have faced arrest and trial since the introduction of the National Security Law in 2020.
Others include Christian activist Joshua Wong who was imprisoned a few months after the law came into effect.
Shortly after the National Security Law was introduced, Cardinal Zen said he was prepared to face trial and imprisonment.