BEIJING—Regulators in China continued a crackdown on internet content by closing hundreds of websites and thousands of mobile apps and calling out tech titan Tencent Holdings Ltd.’s news app for spreading “vulgar” information.

In the past three weeks, the Cyberspace Administration of China has wiped nearly 71 million items of “harmful” information off the web, closed 733 websites and shut down 9,382 mobile apps, the agency said Wednesday.

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