Zambia's prisons are the focus of a new report published by Human Rights Watch. Police brutality is widespread, the report says, with inmates regularly beaten with metal bars, hammers, or electrified rods.

Director of Health and Human Rights division at Human Rights Watch Joseph Anon says interviews with inmates at Zambia's prisons unearthed widespread abuses.

"What we found were that the police routinely would bring in large numbers of people including family members of suspects and then they would torture people," Anon said.

He says the brutality that was recounted was severe.

"They were hung by their feet upside down, sometimes sexually assaulted, beaten on their feet, on their hands, on their backs with metal bars or with wooden batons, sometimes with electric tazors," Anon added.

Human Rights Watch says many prisoners had scars and injuries as evidence of their treatment.

Some female detainees said they had been offered their freedom in exchange for sex.

Human Rights Watch carried out its research in six Zambian prisons. It says officials in Zambia have not responded to letters from the body requesting an investigation.

Amon says Zambian police officials have told Human Rights Watch that the incidents of abuse are isolated. But Anon says the accounts that he and his fellow researchers heard were consistent and indicated that beatings are widespread and systematic.

"I think that it's happening with the knowledge of the police authorities and without any adequate measures of accountability or insistence that these practices be ended," Anon said.

A Zambian police spokesman refused to comment when contacted about the report by the Associated Press.  Other police spokespeople in Zambia were not immediately available for comment.

A Human Rights Watch report published earlier this year highlighted the poor conditions in Zambia's prisons. It said overcrowding is a major problem and some prisoners spend years in prison waiting to be tried. It said HIV and tuberculosis are rife and regularly go untreated.