Several unions from different professional sectors said on Sunday they would devise guidelines for their members on how to uphold their professional autonomy in light of what they described as "political persecution" by the government.
Unions representing medical workers, journalists and social workers said they felt, for different reasons, that they were coming under pressure from officials.
One of the groups involved, the Hong Kong Social Workers' General Union, said it noticed worrying signs that there had been "subtle" changes to how things are run in the social welfare sector.
It revealed that at least two organisations had received police inquiries about their funding records, with one of the NGOs feeling it was being targeted by the government.
"They're very worried that they could be accused of offering or accepting advantages, or [offences] related to foreign forces, or money laundering," said Cheung Chi-wai of the social workers' general union.
Cheung pointed out that this raised concerns that records of services and clients could be affected.
He also accused the government of trying to "threaten' different professions, noting its decisions to appeal against the acquittal of social workers who were arrested while providing services in the field during last year's social unrest.
"This a means to destroy your profession, so that you will no longer operate under your professional autonomy," he said.
The chairman of the Journalists Association, Chris Yeung, said he fears the government could further tighten its grip on reporters and hamper the role of the Fourth Estate. He noted the recent decision to charge an RTHK producer over the use of traffic equipment and the news that the police had decided earlier this year to narrow its definition of the media.
And the union representing hospital workers said it had become the Hospital Authority's nemesis after it organised a strike to the push the authorities to seal the border to prevent the spread of the coronavirus in the early stages of the outbreak.
"All these different kinds of attacks are an alarm, and tell a strong message to the civil society and to these professional people [about] what kind of professionals could be allowed or accepted in the future if you want to carry on your profession," said Carol Ng, the chairwoman of the Confederation of Trade Unions.
She said the unions banding together was a good start for them to start defending the integrity of their professions.