"Airports Company South Africa has replaced security guards in the affected operations as a precautionary measure while investigations continue. Security measures around the airport have been further heightened," Acsa said in a statement.
"Management of Airports Company South Africa is deeply concerned by this robbery and the manner in which it took place. We are working closely with law enforcement agencies to support both the investigation of this robbery and to establish what further measures will be taken."
Acsa said that the armed robbery took place on Tuesday evening, when a bakkie with "what appeared to be police markings" on it pulled up at a restricted access gate, North Gate 1, at around 7.23pm.
The bakkie was followed by a white Ford Focus, both cars had their sirens and blue lights activated, Acsa said.
"The vehicles were occupied by several armed men, some of whom were in South African Police Service (SAPS) uniforms. When requested to validate their credentials, the men produced firearms, rounded up security staff in the security checkpoint and ordered them to lie on the floor," Acsa said.
"The robbers proceeded to gain access to the air-side of the airport where they removed an undisclosed amount of money from a sealed container. No shots were fired and no injuries were reported. The bakkie and the Ford Focus then exited through the same point of entry at 7.45pm."
The South African Police Service established an investigative task team comprising of Crime Intelligence, and the Hawks. Acsa said that the team had been working around the clock in an effort to trace the robbers.
"Thus far the two vehicles involved in the robbery have been recovered in Mamelodi, east of Pretoria. It was established that the bakkie had been made to look like an official police vehicle."
Police could however not confirm media reports that the stolen cash was in excess of R24 million.
Hawks boss Lieutenant General Mthandazo Ntlemeza urged the public to assist investigators with any information they could have on the “weird robbery”.
“This is a serious matter and as the Hawks we will put out all stops to uncover the truth behind this weird robbery. We do not want to speculate at the moment but we are confident that people responsible for the robbery will be brought to book,” Ntlemeza said.
“The airport is a National Key point and it’s safely is of paramount importance. We call upon the public to provide with any information regarding this matter which will assist with the investigation.”
Acsa added that the safety of passengers, staff, stakeholders and visitors to the airport was not compromised during the robbery.
"We can assure passengers and visitors to the airport that their safety and security remains our top operational priority. Operations at OR Tambo International Airport were not affected and the airport is functioning normally," Acsa said.
South African Banking Risk Information Centre (Sabric) has on Wednesday, expressed outrage at the multi-million rand cash-in-transit heist.
In a statement on Wednesday, Sabric chief executive Kalyani Pillay, said it was evident that the heist was executed using accurate information, which resulted in the criminals getting away with millions of rand in cash.
Pillay said this incident exacerbated an already dire situation of attacks on cash-in-transit vehicles and staff.
“The brazenness of the criminals involved, as well as the ease with which access was gained to such a secure area is of huge concern to us,” Pillay said.
Sabric is a not-for-profit company formed by South African banks to support the banking industry in the combating of crime.
During 2016, Sabric recorded 269 cash-in-transit incidents nationally compared to 249 incidents in 2015. For the period 2017 year to date, 57 incidents have been recorded thus far.
“We know that syndicates perpetrating these kinds of crimes are highly skilled and organised,” Pillay said.
Spokesperson for Directorate for Priority Crime Investigation (the Hawks), Brigadier Hangwani Mulaudzi , was not immediately available to give an update but confirmed on Tuesday that a gang stole an undisclosed amount of money at the OR Tambo International Airport.
“The matter is receiving serious attention from the law enforcement agencies in the country. We are not in a position to divulge the details pending the outcome of the investigation,” Mulaudzi had said.African News Agency