You are not permitted to download, save or email this image. Visit image gallery to purchase the image.
South Africa's police force is struggling to overcome a reputation for being heavy-handed and trigger-happy almost two decades after apartheid ended.
An internal investigation is being conducted and criminal procedings have been brought against the two policemen.
"We condemn the behaviour in the strongest possible terms of what we witnessed in the video," Arno Lamoer, the provincial police commissioner, told journalists.
He said the man, an unidentified foreign national who was naked, has not laid any charges against the policemen, who are seen punching and kicking him in the genitals, after answering a call-out on robbery complaint.
The man was released without being charged.
Lamoer said it was unclear if the man was already naked or whether the police officers tore off his clothes while grappling with him on the road as people looked on.
In the footage, taken from an office block, a woman opens a window and shouts "police brutality" before an officer moves towards her.
Last year nine policemen were charged with murdering a Mozambican taxi driver who was handcuffed and dragged behind a police vehicle in full view of bystanders.