Protestors gather on the streets in Zimbabwe during demonstrations. Six Zimbabwean political activists were abducted from their homes at night and beaten by armed men this week, ahead of planned street demonstrations. File photo: Tsvangirayi Mukwazhi/AP Photo.

HARARE - Six Zimbabwean political activists were abducted from their homes at night and beaten by armed men this week, ahead of planned street demonstrations by the main opposition party, a coalition of rights groups said on Thursday.

The opposition Movement for Democratic Change (MDC) has called Friday's protest against the handling of the economy by President Emmerson Mnangagwa's government.

Police have said they believe the protests will turn violent. The MDC says the demonstrations will be peaceful.

The Zimbabwe Human Rights NGO Forum, a coalition of rights groups, said it suspected state security agents were behind the abductions and beatings of the rights activists accused of planning the protests.

"The developments so far point to a real risk that the people of Zimbabwe's fundamental freedoms are once again in danger and this must be stopped before it gets out of control," Jestina Mukoko, who chairs the forum, told reporters.

"Sadly, these developments remind us of the atrocities committed earlier this year in January," she said, referring to a military crackdown on violent protests that led to the death of more than a dozen people.

Nick Mangwana, the secretary of the information ministry, said on Twitter he was not aware who was responsible for the attacks on activists and that these should be investigated.

Zimbabweans are enduring the worst economic crisis in a decade, marked by soaring inflation and shortages of hard currency, fuel, electricity and bread, which has fuelled public anger against Mnangagwa's government.

Hope that the economy would quickly recover and political rights expanded after longserving ruler Robert Mugabe was removed in a coup in 2017 has turned to despair amid the economic hardship.

Police spokesman Paul Nyathi said law enforcement officers had recovered stones and catapults stashed in central Harare, which he said were part of evidence that showed that Friday's demonstrations would be violent.

He said he was not aware of the abductions reports.

The police have since Wednesday increased patrols in the capital Harare ahead of the MDC protests, which the party said will be rolled out in other cities next week.

"Police reiterates that security services will not fold hands and allow violence, destruction of property, intimidation, threats and clandestine night acts of violent agitation to take centre stage," Nyathi said in a statement.

In January, the protests against a sharp fuel price hike resulted in looting of shops. When the army was deployed, some protesters were shot and rights groups said dozens of activists were seized from their homes in night raids and badly beaten by security agents. 

Reuters