Auditor-General Kevin Brady is to investigate the management of multi-million-dollar Auckland City Council paving contracts.
The contracts were reviewed by the council this year after it was found that a council officer evaluating them had accepted a Christmas ham from the main tenderer.
Council transport committee chairman Ken Baguley says that since the Christmas ham revelation, more than 100 allegations surrounding the contracts have been raised.
Mr Baguley says they have been investigated and no evidence of wrongdoing has been found, except for the ham.
Nonetheless the council's chief executive has asked Mr Brady to investigate.
Grant Hewison, a lawyer specialising in local government matters, says it is unusual for the auditor-general to look into the management of specific council contracts.
Mr Hewison says the complexity of the investigation means it could take up to a year to complete.