Facebook and its private messaging service WhatsApp, as well as Twitter, will stop reviewing requests from Hong Kong for user data while the companies evaluate a new national security law imposed on the city by the Chinese government.

The new national security law was revealed at the end of June and has already had a chilling effect on the city that has long been a haven for more open free speech and Internet access than mainland China. People in Hong Kong have started deleting their social media accounts and an upstart political party disbanded. The law gives Beijing wide reach to crack down on those in Hong Kong who criticize its government, including imposing life imprisonment.

Facebook spokesperson Andy Stone said it would stop considering requests from Hong Kong until the company reviewed the law and consulted with international human rights experts.

“We believe freedom of expression is a fundamental human right and support the right of people to express themselves without fear for their safety or other repercussions,” Stone said in a statement.

Law enforcement and government agencies can ask Facebook to hand over information about user accounts and their online activities as part of investigations or other concerns. Facebook says it works “with the law enforcement community to promote safety, on and offline,” but that it reviews every request to make sure it is legitimate.

Facebook considers law enforcement and government requests for user data on a case-by-case basis, requiring the agency to submit a request that Facebook reviews.

Twitter said it immediately paused data requests from the Hong Kong government last week when the law went into effect.

“Given the rapid pace at which the new National Security Law in China has been passed and that it was only published in its entirety for the first time last week, our teams are reviewing the law to assess its implications, particularly as some of the terms of the law are vague and without clear definition,” Twitter spokesperson Ian Plunkett said in a statement. The company said it had “grave concerns” about the intention of the law.

Facebook and Twitter are blocked in China but are accessible in Hong Kong, where residents have historically had less oversight from Beijing under the “one country, two systems” commitments. Already, human rights advocates have decried the passage of the new national security law, partly because China did not release a draft for the public to review before it took effect.

U.S. tech companies have mostly maintained a cordial relationship with China where many have some operations though most American social media is blocked in the country. The reaction to the national security law could put pressure on the delicate relationship.