Those eligible can access the British job market at any skill level and without a salary threshold, but won't have access to public funds.
The UK introduced a special, limited type of British nationality in the 1980s for people who were a "British dependent territories citizen by connection with Hong Kong." The passports did not confer nationality or the automatic right to live and work in Britain, but entitled holders to consular assistance from UK diplomatic posts.
Britain handed over Hong Kong, its former colony, to Chinese rule on July 1, 1997 under a "One Country, Two Systems" framework that was supposed to guarantee the city a high degree of autonomy and Western-style civil liberties not seen on mainland China.
The new national security law, enacted just ahead of the 23rd anniversary of Hong Kong becoming a special administrative region of China, criminalises subversive, secessionist or terrorist activities and collusion with foreign forces to intervene in the city's affairs.
In some cases, mainland China will assume legal jurisdiction and suspects could be sent there for trial.
The changes are seen by many as Beijing's boldest move yet to erase the legal firewall between the semi-autonomous territory and the mainland's authoritarian Communist Party system.
Beijing has said that Britain's move to offer refuge to Hong Kong residents constitutes interference in internal matters.
- AP