Fraudulent activity during the Christchurch rebuild should be acted on quickly rather than mopped up afterwards, departing Serious Fraud Office chief executive Adam Feeley says.
His comments come after Deloitte international corruption expert Peter Dent last week warned of the potential for huge amounts of fraud as the systems in place for the rebuild get stretched to the limit.
Mr Feeley said enforcement and regulatory agencies had made the mistake of mopping up after the fact at failed finance companies - but the office would not let that happen in Christchurch.
"It's incredibly important that we don't mop afterwards - we act now, we act in a very co-ordinated fashion, and we act in respect of what we know to be the problem,'' he told TV3's The Nation.
"The problem is at the moment, we're not sure what the problem is. But we every reason to believe - unless New Zealand is some unique anomaly in the world - that post-natural disaster you have fraud, and you have fraud on quite a big scale.''
The Serious Fraud Office would focus on three key areas in Christchurch.
"One is around public awareness - to get people to speak up, to come and contact us, police or other agencies if they see things either within their work or just publicly going on that they have concerns about.''
The second was to use intelligence "a lot more cleverly''.
"You need to analyse data, and the sheer volume of data that happens after a natural disaster means you have to be more sophisticated in the way you look for anomalies that might suggest fraud.''
The third and most important focus was to act quickly.
"Far more quickly than we have in the past.''
Mr Feeley said the office would use methods as unsophisticated as hearing something in a pub.
He said it seemed taboo in New Zealand to "snitch'' but people needed to speak up if they knew about crimes being committed.
"It's New Zealand - we know what's going on and we want to encourage that culture,'' he said.
"It is very, very rare that people commit crimes without someone knowing there is a problem happening.''
Mr Feeley leaves the Serious Fraud Office next month to become the chief executive of the Lakes District Council in Queenstown.