One of Taiwan’s largest pension funds has guided outside firms against using Hong Kong-registered entities to manage its money, according to people familiar with the matter, underscoring the geopolitical challenges facing the financial hub as it deepens ties with mainland China.

The Bureau of Labor Funds, which manages about $235.2 billion, has been verbally asking third-party managers to exclude Hong Kong entities from its contracts since last year, the people said, asking not to be identified because the information is private.