SHIPPING companies are discreetly moving operations out of Hong Kong and taking vessels off its flag registry to avoid geopolitical risks, Reuters reports.

Behind these low-profile moves, six shipping executives say they are concerned that their ships could be commandeered by Chinese authorities or simply hit by US sanctions in a conflict between Beijing and Washington.

Beijing's emphasis on the role of Hong Kong in serving Chinese security interests and growing US scrutiny of the importance of China's commercial fleet in a possible clash over Taiwan, are causing unease across the industry, sources told Reuters.

The US Trade Representative's office last month proposed levying steep US port fees on Chinese shipping companies and others that operate Chinese-built vessels, to counter China's "targeted dominance" of shipbuilding and maritime logistics.

Washington in September warned American businesses about growing risks of operating in Hong Kong, where the US already applies sanctions against officials involved in a security crackdown.

Hong Kong for more than a century has been a hub for shipowners and the brokers, financiers, underwriters and lawyers supporting them. Its maritime and port industry accounted for 4.2 per cent of GDP in 2022, according to official data.

The outflow of ships since 2021 marks a reversal for Hong Kong's registry, which official data show grew roughly 400 per cent in two decades following 1997.