Senior managers at the Johannesburg Roads Agency (JRA) have been suspended after a series of forensic investigations found they had flouted provisions of the Municipal Finance Management Act.

"Disciplinary processes have been established and the implicated individuals, including the current managing director of the JRA, have been suspended," mayor Herman Mashaba said in a statement on Tuesday.

"The investigations were initiated following an expose by Carte Blanche in the first half of 2018. The city appointed Nexus, an external independent forensic firm, to handle the investigation."

Cases against the officials related to appointments inherited by the multi-party government.

"The most notable of these matters included the repairs of the M1 double-decker bridge awarded to White Hazy in 2015," said Mashaba. "The investigation has revealed that the company's bid was fraudulent in that claims of personnel and relevant experience were falsified.

"Rather than retaining all monies owed and the bank guarantee as collateral to protect the losses in JRA's investment into this project, these monies were returned to White Hazy and the bank guarantee was not utilised as collateral. This was counter to both legal opinions and the MFMA."

Mashaba said the stability of the agency was essential to the performance of the city to address "inherited" backlogs in "our road network with more than 4,000km of roads and 700 bridges in poor condition".