Police brass have issued a strong warning to any of their officials who might be involved in crime.
The warning came after a constable in the VIP protection unit was arrested along with five accomplices before they could attack a cash van in GaRankuwa, north of Pretoria, on Tuesday.
Police said the constable was on suspension for allegedly being involved in a similar crime.
"Any official who is involved in crime will be dealt with in the harshest way," said national spokesman Director Sally de Beer. "The officer has already been suspended and will face criminal charges and a disciplinary hearing."
De Beer said the constable and his five co-accused, whose names will be released after they have appeared in court, were arrested after police received information about a planned robbery.
"We received the information and were able to respond. A Protea Coin cash van was unloading money at an ATM in the area. Detectives were sent to the area and they arrested the men before they could strike."
She said two cars the gang had used, a Nissan Sentra and an Opel Monza, and three pistols were recovered at the scene.
The men, aged between 25 and 30, are expected to appear in the Brits magistrates' court today.
Police and Prisons Civil Rights Union national spokesman Benzi ka-Soko said any police officer who was involved in crime should "face the full might of the law like any other criminal."
He said the union condemned any police involvement in crime.
In April three constables and two accomplices were arrested after the bombing of a First National Bank ATM in Jouberton, Klerksdorp, in North West. A shootout ensued between the gang and police.
The policemen are Charles Legwale, 26, and Lucas Serole, 32, of the Mogwase SAPS, and Gabonakgosi Hlongwane, 30, of the Klerksdorp detective division.
Their alleged accomplices are Lawrence Mantshiyo, 35, and Modise Letsatsi, 38.