BEIJING (AP) — Chinese authorities have further tightened controls of social media in the country, saying that people who post comments deemed libelous and that are retweeted 500 or more times will face defamation charges and up to three years in prison.

The official Xinhua News Agency cited judicial authorities as saying that the new rules will also apply to people whose posts are viewed by at least 5,000 Internet users.

The decision issued Monday comes as authorities have waged a campaign to clamp down on what they've termed "online rumors." State media have also accused some microbloggers of undermining socialism and promoting Western values through lies and negative news.

Many online personalities have amassed substantial followings and some call attention to social injustices and question government policies.