The clean-up, targeting mass-publication accounts as opposed to those used for personal communications, cracked down on accounts masquerading as those of public organisations and media groups, as well as accounts spreading rumours and content that is lewd, pornographic or violent, state-run Xinhua news agency reported.
Other reasons for the accounts being punished included publication of illegal advertisements, disturbing ethnic unity, committing libel and violating privacy, according to a statement released today by the State Internet Information Office, citing Tencent, its parent company.
As of Aug 25, 46 mass-publication accounts had been permanently shut down, and another 311 disabled, with suspension durations ranging from seven to 90 days.
Tencent's swoop followed a regulation issued earlier this month stipulating that non-media instant messaging accounts must be certified by service providers and put on record by administrative authorities in order to release or re-post news stories.
The rules urged users to vouch for the authenticity of the information provided, abide by the law and uphold national interests, public order, the rights of other citizens, social morality and the socialist system.
More than 800 million people use instant messengers in China, sending more than 20 billion pieces of information every day.