Zen, a former bishop of Hong Kong, was arrested along with the singer and actor Denise Ho, the lawyer Margaret Ng, and the scholar Hui Po-keung.

“The Holy See has learnt the news of Cardinal Zen’s arrest with concern and is following the development of the situation very closely,” the Vatican said in a statement.

Local reports earlier suggested the arrests were related to their roles as trustees of the 612 Humanitarian Relief Fund, which provided legal aid and other
financial help to people who took part in the 2019 pro-democracy protests that were quashed by security forces.

This week’s arrests were the authorities’ latest move in enforcing the controversial national security law, which was imposed on the city in June 2020.
The legislation bars secession, subversion and collusion with foreign forces. They also came less than a week after the incoming chief executive, John Lee,
was selected by a small number of elite voters on Sunday.