Social media users and broadcasters found to be generating, sharing, spreading or in possession of information deemed to be subversive or aimed at causing "unrest" will be arrested, according to the Posts and Telecommunications Regulatory Authority of Zimbabwe (Potraz).

The government has apparently tightened the screws on radio and television stations, as well as social media platforms including WhatsApp, Facebook and Twitter.

The Broadcasting Authority of Zimbabwe (BAZ) said communication to local radio and television stations that they have to control what is said on their stations.

In a letter titled Programme Content and Presentation dated 4 July 2016, Obert Muganyura, CEO of BAZ reminded the broadcasters that "in your portrayal or reportage of news and current affairs programing ... you do not broadcast programs that incite, encourage or glamorise violence or brutality".

The directive added that broadcasters be technically equipped to gag offensive phone-ins during live programs. "We also advise that you be technically equipped to handle live programmes and avoid broadcasting obscene and undesirable comments from participants, callers and audiences," the broadcasting authority chief said.

Zimbabwe has a handful of private radio stations and four state owned radio stations.

The state has also moved in to curb free speech on social media, according to media campaigners.

This came after Potraz issued a notice yesterday warning that "all SIM cards in Zimbabwe are registered in the name of the user."

As protests spread in Harare and other parts of the country yesterday, Zimbabweans woke up to curbed WhatsApp connectivity. The application, which was not accessible from early Wednesday until mid-day, is now functional.

No reason has been given for the outage.

"These disturbing pronouncements are a repeat of similar threats issued by President Mugabe and Mandiwanzira a few weeks ago against the use of social media to communicate what government deems unpalatable," according to the Zimbabwe chapter of Media Institute of Southern Africa.

The Institute called on "all relevant authorities and internet service providers to desist from eroding citizens' rights to freedom of expression and access to information in violation of the country's constitution and regional and international instruments on the promotion of civil liberties."