China warned against 'clear, serious' violation of treaty with UK

The UK believes that Beijing's move violates Hong Kong's autonomy, threatens the freedoms and rights protected by the joint declaration, and is in direct conflict with the territory's Basic Law, its mini-constitution.

Addressing the media on Wednesday, Johnson said: "We have made clear that if China continued down this path, we would introduce a new route to those with British National (Overseas) status to enter the UK granting them limited leave to remain with the ability to live and work in the UK and thereafter to apply for citizenship, and that is precisely what we will do now."

Describing the Chinese move as "a grave and deeply disturbing step", Foreign Secretary Dominic Raab promised that UK would honour its commitment to the people of Hong Kong.

"We will grant BN(O)s five years' limited leave to remain, with the right to work or study. After these five years, they will be able to apply for settled status.

"After further 12 months with settled status, they will be able to apply for citizenship. This is a special, bespoke, set of arrangements developed for the unique circumstances we face," Raab told MPs.

Raab did not set out any plan to sanction China or individual Chinese officials through new legislation due to be introduced by the Foreign Office this month.

He also said he was hopeful that other countries in south-east Asia would also offer asylum to Hong Kong citizens wanting to leave.

"China has broken its promise to the people of Hong Kong under its own laws. China has breached its international obligations to the UK under the joint declaration."

Hong Kong's autonomy, which now faces threat from Beijing's imposition of a new security laws, was guaranteed under the "one country, two systems" agreement of the 1984 joint declaration signed by the then Chinese premier, Zhao Ziyang, and British Prime Minister, Margaret Thatcher.

The Foreign Office said: "There are 349,881 holders of BN(O) passports and the government estimates there are around 2.9m BN(O)s currently in Hong Kong. The scheme is for eligible BN(O) status holders and their immediate family dependants."