Facebook and WhatsApp are "stopping" cooperation with Hong Kong police requests for user information.
Several countries, including the United Kingdom, have criticized China for imposing new security laws, which they believe threaten the territory's long-standing autonomy.
Facebook said it would stop considering the requests, "pending further evaluation" of human rights issues.
No personal information about users in the region has been retained or disclosed by his Hong Kong office, he added.
"We believe that freedom of expression is a fundamental human right and we support people's right to express themselves without fear for their own safety or other repercussions," said Facebook.
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Facebook-owned WhatsApp said it "believed in people's right to have a private online conversation" and "we are committed to providing private and secure messaging services to our users in Hong Kong."
Both platforms are blocked in mainland China, but have benefited from Hong Kong's much wider access to the Internet thanks to its freedoms as a special administrative region.
What does Facebook offer the police?
WhatsApp has end-to-end encryption enabled by default, so it cannot read or share messages sent between two users with police officers.
On Facebook Messenger, however, encryption is not the default option: it must be activated manually by users.
Both platforms claim to be able to disclose user data, in accordance with the law of the country in question.
But WhatsApp adds that successful requests for this information must meet "internationally recognized standards including human rights, due process and the rule of law."
In the United States, both platforms require a quote to provide "basic subscriber records" such as the person's name, Internet Protocol (IP) address, and email address.
Additional information about the subscriber may require a court order.
And a search warrant is needed for the account contents:
- On Facebook, it includes "messages, photos, videos, posts and location information
- On WhatsApp, it means profile photos, contact lists and group information
Hong Kong, once British territory, was returned to China in 1997, provided it would have enjoyed special freedoms for 50 years.
The United Kingdom claims that China has broken that agreement and offers citizenship to as many as three million Hong Kong residents.
Meanwhile, the United States - where it is based in Facebook - is considering whether to remove Hong Kong's favorable trading conditions.
Security laws introduce new crimes, including conspiracy with foreigners to provoke "hatred" against the Chinese government or Hong Kong authorities, with sanctions up to life imprisonment.
As soon as the older members of the democratic groups entered into force, they resigned, fearing they would be prosecuted.
And the books written by democracy activists have been removed from libraries.
