US Secretary of State Mike Pompeo on Monday lashed out at what he called China's "Orwellian" moves to censor activists, schools and libraries in Hong Kong under new sweeping security law.

Axar.az reports citing foreign media that authorities in the financial hub have ordered schools to remove books for review under the new law, which has criminalised certain opinions such as calls for independence or autonomy.

Libraries in Hong Kong said they were pulling titles written by a handful of pro-democracy activists.

"The Chinese Communist Party's destruction of free Hong Kong continues," Pompeo said in a sharply worded statement.