The 94-year-old Cardinal Joseph Zen, one of Asia's highest-ranking Catholics, was among those convicted of failing to properly register the fund as a society.

His case was closely watched for its implications on the the freedom of association under a sweeping national security law imposed by Beijing on Hong Kong that put an end to months of huge pro-democracy protests in 2019.

A panel of three judges upheld a previous ruling that the fund constituted a "society", which would require registration or exemption from registration with authorities.

"Nothing in the evidence suggests that any individual including the appellants would be subject to an unacceptably harsh burden by the restrictions imposed by the registration scheme on their exercise of the right to freedom of association," the judges said Thursday.

Zen, using a walking stick, appeared at the court hearing with four other appellants including activist and singer Denise Ho, and veteran human rights barrister Margaret Ng.

Ng told reporters outside that the group planned to appeal to the Court of Final Appeal.

"The definition of 'society' is very very broad, it could affect a lot of people," she said.

"It will make people think that if a few people get together to do something, they could fall under the definition of society, and so under the regulation, they will need to register with police, or get an exemption."

During the trial, prosecutors had argued that part of the fund, which raised as much as HK$270 million, "was used for political activities and non-charity events", including donations to protest groups and activists overseas.

The defence argued that the fund was "merely a name given to a sum of money" and the defendants did not form any society.

It also challenged the law's vagueness, saying it imposed disproportionate restrictions on the freedom of association.

Zen's group acted as trustees and secretary of the now-defunct "612 Humanitarian Relief Fund", which helped pay legal and medical costs for people arrested during the 2019 unrest.

The fund disbanded in 2021 after national security police demanded it hand over operational details, including information about its donors and beneficiaries.