China’s top leader warned that Beijing will go after so-called "platform” companies that have amassed data and market power, a sign that the monthslong crackdown on the country’s internet sector is only just beginning.

President Xi Jinping on Monday chaired a meeting of the communist party’s top financial advisory and coordination committee, ordering regulators to step up oversight of internet companies, crack down on monopolies, promote fair competition and prevent the disorderly expansion of capital, according to state broadcaster CCTV. Internet companies need to enhance data security and financial activities need to come under regulatory supervision, CCTV also reported.

The unusually strongly worded comments from Xi and his lieutenants suggest Beijing is preparing to amplify a campaign to curb the influence of its largest and most powerful private corporations, which has so far centered mainly on Jack Ma’s Alibaba Group Holding Ltd. and its affiliate Ant Group Co. The term platform economies could apply to a plethora of mobile and internet giants that offer services to hundreds of millions, from ride-hailing behemoth Didi Chuxing to food delivery giant Meituan and e-commerce leaders like JD.com Inc. and Pinduoduo Inc.