The shock suspension of Ant Group Co.’s $35 billion initial public offering is just the beginning of a renewed campaign by China to rein in the fintech empire controlled by Jack Ma.

Authorities are now setting their sights on Ant’s biggest source of revenue: its credit platforms that funnel loans from banks and other financial institutions to millions of consumers across China, according to people familiar with the matter.

The China Banking and Insurance Regulatory Commission plans to discourage lenders from using Ant’s platforms and has already asked some to ensure their portfolios are compliant with stringent draft regulations announced Monday, said the people, who asked not to be identified discussing private information.