A taxi driver in South Africa died after being handcuffed to a police vehicle and dragged hundreds of yards, it has been alleged.
Independent police investigators are looking into the claims after video footage emerged showing a man being dragged along a road behind a police van.
The man, named locally as 27-year-old Mido Macia from Mozambique, was later found dead in a police cell in Daveyton, Johannesburg, on Tuesday.
Officers have claimed they put Mr Macia in a police van in order to take him to a police station on the East Rand, and cannot explain how he later died.
But the video, obtained by South Africa's Daily Sun newspaper, shows officers struggling to overpower a man - believed to be the taxi driver - before attaching him to a point at the rear of their vehicle and then driving off leaving him hanging outside.
Officers are seen restraining the man and handcuffing him to the van
At one point they attempt to carry his legs while the vehicle is moving forward but have to drop him as the police van speeds up.
The footage then shows the man trying to stay on his feet as he is dragged behind the vehicle for several hundred metres.
The person filming the incident attempts to keep up with the truck dragging the taxi driver, but has to give up as the vehicle is going too fast.
The van then starts to move away with the man hanging on
Inmates in the cells he was taken to have claimed he was later beaten to death by police.
The incident has inflamed local feelings and Sky's Alex Crawford who is outside the police station says a crowd has gathered to protest.
South Africa's Independent Police Investigation Directorate (IPID) said on Wednesday that officers had initially attempted to arrest Mr Macia because he was allegedly obstructing traffic.
At one point they lift his legs but have to let go when the van speeds up
IPID spokesman Moses Dlamini said: "We are investigating an incident involving the death of man, allegedly at the hands of the police. We are shocked by the footage which has been released.
"The circumstances surrounding his death are still allegations ... let's find out what really happened," he said.
He said there were reports Mr Macia had tried to disarm a police officer before the attack.
The taxi driver was then allegedly beaten once inside the police holding cells.
He is understood to have been found dead by another police officer later the same day.
The van then starts to accelerate away and the suspect is dragged behind
Mr Dlamini told the South African website News 24 that an investigation had begun before Mr Macia's death into allegations he carried out an assault resulting in grievous bodily harm.
A post-mortem on the dead suspect indicated he had died from head injuries with internal bleeding.
Police in South Africa are known for heavy handedness when dealing with the public, and the police watchdog is handling numerous cases of police brutality.
In the 12 months before March 2010, according to Amnesty International, there were 920 complaints of serious assault and 294 deaths in custody.
The police department could not confirm if the officers had been suspended.