As a finance hub with an internationally respected legal system, Hong Kong has long marketed itself as a reliable business gateway to authoritarian China.

But swirling geopolitical tensions — and China’s crackdown on dissent in the city — have made that business environment less smooth the last two years.

And things could be about to get even more complicated.

In June, China passed a broad anti-sanctions law in response to US and European punishments sparked by Beijing’s treatment of Hong Kong and its Uighur Muslim minority in Xinjiang.

Its powers include denying visas, deportation, or seizing assets of those who formulate or comply with sanctions against Chinese businesses or officials.

Foreign companies can be sued in Chinese courts for applying sanctions and the law can also be wielded against family members.

Then earlier this week Hong Kong’s chief executive Carrie Lam confirmed the anti-sanctions law would soon be applied in the financial hub in some form.

International businesses — in particular banks — are now scrambling to work out what that could mean for them, fearful that they could be caught between competing sanction regimes.

“If the law is to be taken seriously, it could be a huge problem if banks in Hong Kong have to enforce US sanctions, and then face prosecution in Hong Kong for enforcing those sanctions,” Julian Ku, an expert in international law at Hofstra University told AFP.

‘Bite the bullet’

Question marks surround what the law might look like.

Chinese state media has said Beijing’s top law-making body is planning to unveil unspecified new measures for Hong Kong and Macau when it meets next week.

Some Hong Kong officials have suggested Beijing could impose the law on the city as it did with sweeping national security powers last year that criminalised much dissent.

“I know some of us may be very concerned,” Secretary for Justice Teresa Cheung told reporters earlier this month. “But I think we shouldn’t be too worried for now.”

Lam, one of the dozens Chinese officials sanctioned by the United States, has said she would rather the law be passed locally to cater for the city’s own legal and business environment.

Such assurances are of limited comfort for people like John, a senior manager working for an international bank in Hong Kong, who fear being caught between an American rock and a Chinese hard place.

“We have no choice, either we shut the whole bank, which many people don’t want to do, or we have to just bite the bullet and continue our businesses,” he told AFP, asking to remain anonymous to speak freely.

China may be wary of forcing foreign banks out of Hong Kong.

The national security law already makes it illegal for companies based there to adhere to foreign sanctions — something the United States highlighted last month in a rare business advisory warning.