China kicked off an investigation into alleged monopolistic practices at Alibaba Group Holding Ltd. and summoned affiliate Ant Group Co. to a high-level meeting over financial regulations, escalating scrutiny over the twin pillars of billionaire Jack Ma’s internet empire.

The State Administration for Market Regulation is investigating Alibaba, the top antitrust watchdog said in a statement without providing further details. Regulators including the central bank and banking watchdog will separately summon affiliate Ant to a meeting intended to drive home increasingly stringent financial regulations, which now pose a threat to the growth of the world’s biggest online financial services firm. Ant said in a statement on its official WeChat account it will study and comply with all requirements.

Once hailed as drivers of economic prosperity and symbols of the country’s technological prowess, Alibaba and rivals like Tencent Holdings Ltd. face increasing pressure from regulators after amassing hundreds of millions of users and gaining influence over almost every aspect of daily life in China.