Two workers at Belfast City Council have been suspended after the local authority was scammed out of £300,000.
There is no suggestion the employees were involved in any sort of criminality and both have been suspended on full pay because of the fraud.
A council statement said: "Senior officers emphasised that there was no suspicion of any council staff being involved and that the fraud was the result of a failure to apply procedures rather than any weaknesses in established security measures."
The police were called in after conmen posing as contractors used bogus bank details to pocket ratepayers' cash.
Alderman Jim Rodgers, chairman of the cross party audit panel which held an emergency meeting to discuss the fraud, said the city council was among a number of organisations caught out by the criminals.
Mr Rodgers said: "We called an emergency meeting of the audit panel to seek assurances from senior officers that our security had not been compromised and to see if our already robust security procedures could be further enhanced."
The council expects to be able to recoup the stolen money from an insurance claim.
Mr Rodgers added: "Our biggest concern was the potential cost to our ratepayers and we have been informed that the council has submitted an insurance claim to recover the amount.
"The panel members were assured that such an incident is unlikely to happen again and this was a failure to comply with security procedures rather than a fundamental failure of our systems.
"We understand the importance of providing information and support to suppliers and other companies with whom we conduct business at this time. The council is in the process of contacting all these companies but if any have immediate concerns they should contact the council as soon as possible."