A misinformation campaign on social media in support of Chinese government interests has expanded to new languages and platforms, and it even tried to get people to show up to protests in the United States, researchers said on Wednesday.

Experts at security company FireEye and Alphabet’s Google said the operation was identified in 2019 as running hundreds of accounts in English and Chinese aimed at discrediting the Hong Kong democracy movement. The effort has broadened its mission and spread from Twitter, Facebook and Google to thousands of handles on dozens of sites around the world.

This expansion suggests Chinese interests have made a deeper commitment to the sort of international propaganda techniques Russia has used for several years, experts said.

Some of the new accounts are on networks used predominantly in countries that...