The central government's top body overseeing Hong Kong affairs voiced strong objections on Sunday to the United Kingdom for breaking its promise on the British National Overseas passport with a plan to grant BNO passport holders UK citizenship.

The Hong Kong and Macao Affairs Office of the State Council said in a statement that the UK has clearly violated its pledge as made in a memorandum before the Hong Kong Special Administrative Region's return to China.

The office said the Chinese and British governments reached consensus long ago on how to deal with the issue of Hong Kong residents holding BNO passports and exchanged memoranda on the understanding in 1984.

In its memorandum, the UK clearly pledged not to confer the right of abode in the UK on holders of the BNO passport who are Chinese nationals in Hong Kong.

On Friday, in response to that plan, the central government and the SAR government announced that on Sunday BNO passports would not be recognized as a valid travel document or proof of identity in China.

Since last year, the UK, in violation of international norms that govern international relations, has spared no efforts to stop the legislation and implementation of the National Security Law for Hong Kong, the office said.

Interference

The citizenship decision is another attempt by the UK to interfere after its futile attempts failed, the statement continued.

The office stressed that the Chinese government stands firm in strictly enforcing the security law and reserves the right to further countermeasures to such a breach of agreement.

In a separate statement by the Liaison Office of the Central People's Government in the Hong Kong Special Administrative Region on Sunday, a spokesperson for the office criticized the UK for using the BNO for a political maneuver under the pretext of the National Security Law for Hong Kong.

The UK has further expanded the scope of the BNO passports' application in an attempt to turn a large number of Hong Kong people into "second-class British citizens", the spokesperson said.

Granting BNO passport holders citizenship in the UK has completely altered the nature of the BNO passport as it was originally understood by China and the UK, the statement continued.

It is legitimate for China to take countermeasures since the UK broke its promise, the office stressed.

Over the weekend, political heavyweights in Hong Kong said BNO passport holders who opt for UK citizenship through the UK decision would lose their permanent residency in the city.

Tam Yiu-chung, a member of the Standing Committee of the National People's Congress, the nation's top legislature, said China has made its stance clear by denying the BNO passport's validity as a travel and identity document.

Losing identity

Lau Siu-kai, vice-president of the Chinese Association of Hong Kong and Macao Studies, warned that those who obtain UK citizenship through the decision could risk losing their permanent residency or Hong Kong residents identity status.

Deprived of those, they would not be entitled to an array of the political rights and social benefits local residents have, he said. They would be treated as foreigners in the city, he added.

What's more, Lau cautioned that with China no longer recognizing BNO passport, those who obtain UK passports under the decision could be denied entry into the Chinese mainland as their UK passports may not be recognized as well, the political scientist warned.

Hong Kong's Immigration Department said on Sunday that inbound and outbound Hong Kong passengers are required to present their HKSAR passports or permanent identity cards as identity proof upon boarding.

Secretary for Justice Teresa Cheng Yeuk-wah said in a blog post on Saturday that there is no clause in the Joint Declaration that provides for UK rights or obligations to Hong Kong after its return to the motherland in 1997.

The UK made the promise that no citizenship would be offered to BNO passport holders in the memorandum reached under the backdrop of the Joint Declaration, she said.