The Serious Fraud Office has executed search warrants at multiple properties in its probe of people linked to Auckland Transport.
The SFO confirmed today it had launched an investigation into people related to the council body and has "reasonable grounds to believe that an offence involving serious or complex fraud may have been committed".
Its investigation involved alleged "irregularities in the procurement of services" and the SFO said search warrants were executed yesterday.
The matter had referred to the SFO by Auckland Transport and acting SFO chief executive Simon McArley said no further comment would be made.
The fraud watchdog's involvement follows Auckland Transport sacking a senior manager last month during an investigation of roading contracts and alleged corruption.