Human Rights Watch urged Zimbabwe's power-sharing government to discipline security chiefs who have declared their allegiance to veteran leader Robert Mugabe ahead of this summer's elections.
"Zimbabwe's unity government is going to have to rein in the security forces and keep them out of politics if the elections are going to have any meaning," said Tiseke Kasambala, HRW's advocacy director for Africa.
With security forces "threatening and attacking Mugabe's perceived opponents, Zimbabweans have little faith in the upcoming elections," he added.
Zimbabwe is to hold elections in the coming months to end a shaky coalition between Mugabe and his longtime rival Prime Minister Morgan Tsvangirai.
The exact date is yet to be fixed but the country's highest court last week ruled that Mugabe must call elections by July 31.
The heads of Zimbabwe's security forces including the army, the police and prison services have made no secret of their allegiance to Mugabe's party, labelling Tsvangirai a stooge of the West.
In a 44-page report, the New York-based rights group accused the army of having "deployed soldiers across the country, intimidating, beating and abusing" Tsvangirai's supporters or those people critical of Mugabe's rule.
Early last month Zimbabwe defence forces commander Constantine Chiwenga vowed not meet Tsvangirai to discuss security sector reforms.
"We have no time to meet sellouts. Clearly Tsvangirai is a psychiatric patient who needs a competent psychiatrist," Chiwenga said.
Police commissioner general Augustine Chihuri also said he would not entertain any attempts to reform the country's security sector.
Zimbabwe security agents were implicated in widespread abuses including killings, beatings and torture during the violent and disputed 2008 presidential election run-off.
"The leadership of the military, police, and internal security agency, the Central Intelligence Organization, has remained unchanged and openly supportive of Mugabe," said the watchdog.
In its report,"The Elephant in the Room: Reforming the Security Sector Ahead of Zimbabwe's Elections" the HRW said Zimbabwean soldiers had a legal obligation to behave professionally and refrain from political activities.
"Zimbabwe's laws and constitution require neutrality and impartiality from the security forces but the security forces have shown no sign of meeting their obligations," Kasambala said.
"The government needs to send a clear message by disciplining and prosecuting security force personnel and soldiers who violate the law for political reasons."
Kasambala urged regional leaders from the Southern African Development Community (SADC) meeting in Maputo on Sunday to assess Zimbabwe's election readiness, to put reform of the security sector on their agenda.
"SADC should make improving the behaviour of the security forces a key pillar of the Zimbabwe roadmap to credible, free, and fair elections," Kasambala said.
"The coming elections are an important step in ending the country's longstanding human rights crisis."
It was the SADC that brokered the power-sharing government reached after the bloody 2008 elections, and the bloc remains the guarantor of that political uneasy deal.
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