BEIJING (AP) — China is targeting popular smartphone-based instant messaging services in a monthlong campaign to crack down on the spreading of rumors and what it calls infiltration of hostile forces, in the latest move restricting online freedom of expression.

Such services incorporate social media functions that allow users to post photos and updates to their friends, or follow the feeds of companies, social groups or celebrities, and — more worryingly for the government — intellectuals, journalists and activists who comment on politics, law and society. They also post news reports shunned by mainstream media.