Auckland Transport has called on external investigators to guide its inquiry into serious allegations of corruption over roading contracts.

The council organisation has stood down a senior manager on indefinite leave during the inquiry, which it was previously conducting in-house while promising to call in the Serious Fraud Office if it could find evidence of wrongdoing.

But chief executive David Warburton said today it had now called for "external forensic accounting advice" from consultants PricewaterhouseCoopers into the road maintenance area of its business.

The accountancy giant is also separately investigating allegations about irregularities over infrastructure contracts at KiwiRail, after being called in by the state-owned company, although no officials have been stood down by that organisation.


Dr Warburton said Auckland Transport was completing the initial phase of its investigation, and the external advice had been sought in parallel with an internal review of procurement procedures.

He could not indicate how long the review might take but said the organisation would continue to keep the SFO and the Office of the Auditor-General informed about any progress.

The manager remained on indefinite leave while the matter was being dealt with "to ensure the integrity and independence of the investigation is maintained."

The SFO confirmed last week that it has spoken to both Auckland Transport and to KiwiRail about their respective investigations, and that both organisations had undertaken to advise it if they found evidence of potential fraud.