HSBC Holdings PLC’s endorsement of a proposed Chinese security law in Hong Kong has begun to widen fault lines over the British institution’s relationship to the city’s masters in Beijing.

The bank’s statement on the eve of the June 4 anniversary of the 1989 crackdown in Tiananmen Square of a looming security law heightened worries among both executives and the rank-and-file over staff conflict, as well as potential blowback on the streets of Hong Kong.

It’s an ever more precarious balancing act for Chairman Mark Tucker, who needs to avoid drawing the ire of clients, employees, investors and policymakers while maintaining access to the world’s second-largest economy. The lender, which was born in the 19th century as the Hongkong and Shanghai Banking Corp. and makes 40 percent of its revenue in Hong Kong and mainland China, is exposed like few other Western companies to a standoff between Beijing and Washington.