Auditors have warned councillors in Aberdeen there is a risk of fraud when cash is collected from parking machines across the city.
A review of the operating system found there was no monitoring in place to police the external company responsible for picking up and banking the money.
Motorists paid £4.8million to the local authority in parking charges in the last year.
A report to the city council’s audit and risk committee has also revealed that Loomis, the firm contracted to collect cash from pay and display machines, does not always empty the boxes on time.
Subsequently, they can become full and do not work properly, which can lead to drivers receiving unnecessary fines.
The council was also criticised in the report from PricewaterhouseCoopers for the time it is taking to process appeals from those who have been given tickets.
There are more than 700 pay and display machines around Aberdeen.
Loomis collects the cash on an eight-week rota, and deliver it to G4S, another contractor, which counts and banks it.
Parking is policed in Aberdeen by the city warden team. Fines for parking illegally are £60, which is reduced to £30 if paid within 14 days.
Liberal Democrat councillor Martin Greig, who sits on the audit and risk committee, said: “The public deserve to have the reassurance that the fees collected through parking income are properly accounted for and handled correctly.
“It is unacceptable for drivers to be prevented from using a machine because of a failure to empty it.
“Systems need to be in place which ensure that an efficient parking and ticketing system is in place.”
Committee convener Callum McCaig said: “The reason we commission audits is to find where there are holes or gaps in the systems and then use that information to fill them.
“Whilst this may not be the best of reports, it is better to know and be in a position to address the problem then correct it.”
Labour councillor Gordon Graham, who also sits on the committee, added: “We need to make sure that officers pay more rigorous attention to how the company operates their procedures.”