HONG KONG — The consequences for mouthing off on social media just got a lot harsher in the People’s Republic.

On Monday, China's top court issued new guidelines stating that anyone who posts "false information that is defamatory or harms the national interest" could go to prison for up to three years if their post is viewed 5,000 times or retweeted 500 times. Repeat offenders can also be deprived of their political rights, according to the Supreme People's Court.

The guidelines also include penalties for business owners who pay to spread rumors about their rivals. Serious offenses can lead to up to five years in prison, according to Xinhua news agency.

The new penalties, which went into effect Tuesday, are the latest sign of the severity of Beijing's effort to take control of China's freewheeling social media, which has exposed corrupt officials and eroded the public's trust in the Party.

Over the last several months, high-profile critics of China's government on Sina Weibo, China's equivalent of Twitter, have been warned to follow the Party line more closely. One Chinese-American writer, Charles Xue, was arrested on Aug. 24 and charged with soliciting prostitutes, as well as being a "rumor monger."

For ordinary people, exactly what constitutes a "rumor" remains somewhat unclear. A spokesman for the Supreme People's Court tried to stress that the rules were not intended to punish well-intentioned whistleblowers.

"Even if some details of the allegations or what has been exposed are not true, as long as they are not intentionally fabricating information to slander others ... they will not be prosecuted on charges of defamation," the spokesman said.

But two recent arrests illustrate how fluid the notion of "false information" can be. Last month, two Weibo users were arrested for fabricating rumors about Lei Feng, a semi-mythical Communist Party hero that the government holds up as an exemplar of morality in its propaganda.

And the new system potentially is open to new kinds of abuse. Beijing commentator Bill Bishop noted in his Sinocism newsletter that "given how easy it is to manipulate social media activity, people will need to be very careful about what they post, as anyone with a grudge or an agenda could quickly and cheaply push a target's message over those thresholds."

"As to what is false, defamatory or harmful to national interests, the definition is not going to be up to the user."