Civil service unions expressed alarm over a report that Beijing is mulling over banning Hongkongers with British National (Overseas) passports from holding public office.
Local media reported on Wednesday night that the central government is considering banning BNO holders from working in public office, in retaliation for Britain's move last July of giving them a path to citizenship. It remains unclear whether "public office" refers to all civil servants, or elected officers and senior officials only.
The proposal could reportedly be discussed at the National People's Congress Standing Committee meeting next week, alongside the suggestion that BNO holders be deprived of the right to vote in elections, though it is less preferred due to potential legal challenges.
Nearly 350,000 Hong Kong citizens were BNO holders as of last February.
Leung Chau-ting, the chairman of the Federation of Civil Service Union, said it won't be surprising if the city sees a wave of resignations among civil servants if such a ban is imposed.
"Some quit their jobs over the oath-taking saga. I don't see why it won't happen again," he said. "There are things people don't want to give up in exchange for a job."
Leung was referring to the new requirement that all civil servants pledge allegiance to the Basic Law and the SAR administration, either by taking an oath or signing a declaration.
He said the BNO ban might drive away the city's professionals, especially younger ones, from civil service jobs, as they are not lacking for high-paid job opportunities.
He also questioned the proposal's feasibility. "Whether a government employee holds a BNO is a matter of personal privacy, so what's the reasoning behind requiring them to disclose this information? And even if he does declare that he surrendered the document, how can you verify this? By asking the UK government?"
Simon Shen Xuhui, an international relations scholar and commentator, wrote on his blog that while the SAR government might not know for sure if its employees are BNO passport holders, one would likely face criminal liability if he was found to have lied about relinquishing the document.
The ban would cause "an extremely huge concussion" and a wave of resignations if it includes all civil servants, Shen said.
Meanwhile, Secretary for Security John Lee Ka-chiu said in a TV interview on Wednesday night that the government would cooperate if Beijing reached any decision over BNOs.
"The BNO is just a travel document, with no consular protection attached to it. Our stance and attitude are clear on this," Lee said.
"The central government has the authority over nationality issues [including BNO passport holders]."