TORONTO -- A dual citizen of Canada and China who has been held prisoner in Hong Kong was recently forced to choose between their two nationalities, Global Affairs Canada says.

Declaring themselves to be Canadian could have meant losing residency in Hong Kong, while declaring themselves to be Chinese would have removed their ability to receive help from the Canadian government.

It's not clear which choice was made in that case, but Global Affairs Canada says it's part of a seeming pattern, with dual citizens of Hong Kong and other nations who have been imprisoned for some time now being told to pick one or the other.

"Canada has expressed its concern to the Hong Kong Government and continues to seek additional information from local authorities on any changes to the treatment of dual nationals," the agency told CTV's Your Morning in a statement.

The issue of dual citizenship, which China does not recognize in Hong Kong, has been in the news over the past week because of the United Kingdom opening a path to citizenship for holders of British National (Overseas) passports, prompting China to derecognize the specially issued passports as valid travel documents.

Cherie Wong, executive director of advocacy group Alliance Canada Hong Kong, said Wednesday that the case of the detained Canadian-Chinese dual citizen is an escalation of tactics that have been used by the Chinese government for some time.

"This dual citizenship issue has always been weaponized by the Chinese Communist Party to suppress dissent and use it to criminalize individuals who they deem as a danger to the regime," she told CTV's Your Morning.

Global Affairs Canada says it "received a first indication" two weeks ago that a Canadian dual-national prisoner had been told to declare their citizenship as either Canadian or Chinese.

The agency said that it is working with "likeminded partners" to protect the rights and safety of dual nationals in Hong Kong, and recommended that any dual nationals looking for help from the Canadian government never identify themselves as Chinese.

"Canadians who wish to receive consular services should present themselves as Canadian to authorities at all times," the agency said.

The government also recommends that Canadians in Hong Kong "exercise a high degree of caution … due to the arbitrary enforcement of local laws." A similar warning is in place for Canadians in China.

Legally renouncing Canadian citizenship in Hong Kong involves filling out a formal application and visiting the Canadian consulate. However, Wong said, the recent experience of the imprisoned dual citizen is a sign that China is willing to ignore those rules.

"A lot of the time the Hong Kong and Chinese government will overlook that formal procedure and claim that anyone who has renounced their citizenship, whether under duress or publicly, is no longer a dual citizen," she said.

Wong said she has friends in Hong Kong who "are very worried about their status [and] whether or not they will be able to come back to Canada" due to the seeming escalation in China's crackdown on dual citizens in Hong Kong.

She said she wants to see the Canadian government do more to advocate for the rights of dual citizens and communicate more clearly about what is happening and what options Canadians in Hong Kong have.