Cardinal Joseph Zen, former archbishop of Hong Kong, appeared in court Tuesday after his unceremonious arrest by Chinese Communist Party officials.

The 90-year-old cardinal, who was arrested with four other pro-democracy advocates, was a trustee of a relief fund used to bail out protesters and pay legal fees, according to Catholic News Agency. The five arrestees are charged with not registering the charity with the government.

All five have submitted pleas of not guilty.

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Zen is set to stand trial on Sept. 19. He has stated he plans to celebrate a Catholic Mass on May 24 in honor of Our Lady, Help of Christians.

The cardinal was arrested last week alongside a group of other freedom activists in the Chinese island city. Zen has repeatedly warned the Vatican of increasing government persecution of religious minorities and anti-communist public figures but has historically received next to no response.

Cardinal Joseph Zen attends Mass

Retired Cardinal Joseph Zen, one of Asia's highest-ranking Catholic clerics, attends Mass at the Holy Cross Church in Hong Kong on May 24, 2022. (Peter Parks/AFP via Getty Images)

Zen previously dismissed fears that he was a target for arrest, stating that he tries not to provoke the CCP. However, he later acknowledged that "no public person who dares to speak freely can feel safe anymore."

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In addition to Zen, the arrested include singer-actress Denise Ho, lawyer Margaret Ng and scholar Hui Po-keung, according to Hong Kong Watch. Each of the individuals was arrested for allegedly supporting protests against the CCP's destruction of democracy in Hong Kong.

Retired Cardinal Joseph Zen

Cardinal Joseph Zen arrives for a church service at St. Andrew's parish in Hong Kong, China, on June 4, 2021. (Chan Long Hei/Bloomberg via Getty Images)

"I want to stress that Hong Kong is a society with rule of law where no organization or individual is above the law and all offenses shall be prosecuted in accordance with law," Chinese Foreign Ministry spokesperson Zhao Lijian said. "We firmly oppose any act that denigrates rule of law in Hong Kong and interferes in its affairs."