Departing Serious Fraud Office (SFO) chief executive Adam Feeley is urging people to report fraud in earthquake-damaged Christchurch so any problems can be tackled early.
He says fraud often occurs after natural disasters and there is no reason to believe the situation in Christchurch will be any different.
"It's incredibly important that we don't mop up afterwards and we act now," he told TV3's The Nation programme on Saturday.
"The problem is at the moment we're not sure what the problem is but we have 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," he said.
His remarks come after the Insurance Council warned that fraud from the Christchurch rebuild could total more than $1 billion.
After Hurricane Katrina, fraud ranged from exaggerated insurance claims to collusion between contractors to identity theft.
Peter Dent, a Deloitte partner from Canada, last week warned of the potential for fraud when systems were overwhelmed by claims.
Mr Feeley said the SFO wanted people to speak up and it would use intelligence information more cleverly.
Mr Feeley has been with the SFO since 2009 and is moving to be Queenstown Lakes District Council chief executive.