HONG KONG (AP) — A 90-year-old Catholic cardinal and five others stood trial in Hong Kong on Monday for allegedly failing to register a now-defunct fund set up to assist people arrested in the mass anti-government protests in the city three years ago.

Cardinal Joseph Zen, who is a retired bishop of Hong Kong, was first arrested in May together with others including singer Denise Ho and barrister Margaret Ng on suspicion of colluding with foreign forces to endanger China’s national security.

While they have not yet been charged with national security-related charges, Zen and five others have since been charged for failing to properly register the now-defunct 612 Humanitarian Relief Fund.

Zen, together with Ho, Ng as well as cultural studies scholar Hui Po Keung and former lawmaker Cyd Ho, were trustees of the fund. A sixth defendant, Sze Ching-wee, was the fund’s secretary.

The Societies Ordinance requires local organizations to register or apply for an exemption within a month of their establishment. Prosecutors say Zen and the others failed to do so.

The case will mainly center around whether the 612 Humanitarian Relief Fund is considered an organization that is obliged to register.

The fund helped pay medical and legal fees for arrested protesters during the anti-government protests in 2019 and later ceased operations in August 2021.

All have pleaded not guilty. If convicted, they face a fine of up to 10,000 Hong Kong dollars ($1,273), with no jail time.

The case has sent shockwaves through the Catholic community, although the Vatican has been muted on Zen’s arrest, stating only that it was monitoring the development of the situation closely.

It also comes as the Vatican is working to renew its agreement with the Chinese government over the appointment of bishops in China, in which Beijing recommends bishops which are then approved and appointed by the pope.

The 12-million strong Catholic community is split between the “underground” church, which recognize the pope, and those who attend state-sanctioned churches controlled by the Chinese Patriotic Catholic Association.

In Hong Kong, where there are about 390,000 Catholics in a population of nearly 7.3 million, the Catholic church has not yet faced mainland-style restrictions on freedom even as Beijing tightens its grip over the city.

Zen has openly criticized Vatican’s deal with China, calling it a “sell-out” of China’s “underground” Catholics that are loyal to the Vatican. He has been seen as a somewhat controversial figure for his open criticism of Beijing and ties with Hong Kong's pro-democracy camp.

The case is also part of an ongoing crackdown on dissent in the city. Following the protests, Beijing implemented a tough national security law that outlaws secession, subversion, terrorism and collusion with foreign forces to intervene in the city’s affairs.

The law has been widely seen as a means to stamp out dissent and has been used to arrest over 150 people since it was implemented, many of whom are pro-democracy supporters and activists.

Most of the city’s outspoken pro-democracy activists are either in jail or have fled the city.