The arrest of a prominent Macau executive in the largest prostitution bust in the city's history shows Chinese President Xi Jinping is broadening his crackdown on corruption to restrict even long-tolerated vices.

Police in the former Portuguese colony arrested Alan Ho, handcuffing him and covering his head with a black hood, for allegedly operating a prostitution ring out of the casino complex of his uncle, Stanley Ho. The elder Ho held a monopoly on gambling in Macau for four decades and SJM Holdings Ltd., the company he founded, is still Asia's biggest casino operator.

The authorities' latest target of the sex industry comes as Xi wages the most sweeping campaign in decades against bribery, embezzlement and other kinds of corruption in an effort to bolster the legitimacy of the ruling Communist Party. Macau casinos that suffered last year from the fallout of Xi's crackdown are likely feeling the noose tighten further, particularly on junket operators, middlemen who bring in high-stakes gamblers from the mainland.