China is proposing to introduce a new security law in Hong Kong that could ban sedition, secession and treason.
The move is likely to provoke strong opposition internationally and in Hong Kong, which last year saw months of pro-democracy protests.
China’s delayed National People’s Congress, its legislature, will debate the issue when it opens on Friday.
Hong Kong’s mini-constitution requires it to bring in such a law but it failed to do so amid widespread opposition.
The so-called Basic Law was introduced when the UK handed back Hong Kong’s sovereignty to China in 1997 and provides certain freedoms not available on mainland.
Beijing has always had the power to enact the national security law into the Basic Law but has so far refrained from doing so.
But Hong Kong is heading for elections to its own legislature in September and if last year’s success for pro-democracy parties in district elections is repeated, government bills could be blocked.