With pressure mounting on the police to reduce crime and push up conviction rates, officers are pushing the boundaries, leaving hordes of physically and mentally tortured victims in their wake.

With experts warning that torture - which when revealed has a severe adverse effect on prosecutions - is on the rise, many say the line between the police and the criminals is blurring.

For Sifiso Makhubu, torture is something he knows only too well.

Accused of the murder of a Johannesburg policeman three years ago, he and four friends endured nearly 12 hours of agonising torture.

"They beat us. The more I pleaded with them to stop, the more they continued," he said.

With his hands handcuffed behind his back to his ankles, his assailants sprayed him with water and pulled a tyre tube over his face.

"They were doing it to all of us. While they would tube one they would spray us with water and shock us with tazers all over . on our faces, between our legs, everywhere.

"They would tell us we were going to die."

After three years, Makhubu's terror has not ended.

His attackers, still based at the same police stations, often greet him when they see him in the streets of Soweto.

"Nothing has happened to them. I won my case against them but they continue to work. They greet me and ask me how I am doing. I am petrified that something will happen, that this time I will never come home," he said.

Peter Jordi, of the Wits Law Clinic, said the police were predators who, with unrestrained violence, hunted down suspects.

Jordi, pointing to shelves of torture case files, said the violence and power associated with torture gave the police a sense of immunity.

"They have become masters at what they do. After 1994 there was an increase in torture which subsided until the 2000s. Since then there has been a definite increase of unprecedented violence from beatings, electric shocks, near drownings to detention without trial.

"Our law enforcers' string of barbaric actions to find their suspect often results in minibus loads of people being tortured before the right suspect is found.

"Torture is occurring en masse with children falling victim.

"Torture is spiralling out of control. It is happening everywhere with those involved simply moving from one police station to another when caught," he said.

Leading forensic pathologist Reggie Perumal said torture was increasing because the police were paralysed in trying to deal with crime.

"Crime is running away and in the frustration, especially in Gauteng, to bring it under control police are turning to torture.

"From the number of private cases I get it is clear that torture and the violence associated with it, especially in terms of electrocutions with tasers, cattle prods and live wires, is increasing," he said.

Independent Police Investigative Directorate spokesman Moses Dlamini said he could not say if torture was becoming more prevalent and also not say if police management was taking torture seriously.

"There are cases in which officers arrested for torture are, the very next day, promoted. The biggest problem is that torture is not a crime. Instead, a policeman who is a suspect in a torture case is charged with assault with intent to commit grievous bodily harm.

"In our legislation there is no such offence as torture. Draft legislation, which will criminalise torture, has yet to be passed.

"Because torture has not been defined we simply don't know the exact number of offences," he said.

Jacob van Garderen, of Lawyers for Human Rights, said his organisation was "gravely concerned" by the number of cases reported to it.

"What is happening is horrific with cases remaining unresolved for long periods.

"Mechanisms to investigate torture are severely under-developed and under-resourced.

"Though South Africa ratified the UN convention against torture, and is compelled to investigate torture, it has yet to ratify the protocol on the convention against torture which would lead to the establishment of oversight bodies for all places of detention," he said.

Amanda Dissel, the Association for the Prevention of Torture's South African delegate, said it was worrying that South Africa had yet to criminalise torture.

"This is precisely why we see such a recurrence of torture.

"There is a problem in South Africa in ensuring that torture cases are dealt with, with the seriousness they deserve."

Police spokesman Brigadier Lindela Mashigo hit back by saying torture was condemned.

"Respect of human rights is part of [police] training."