Labour and the Greens want an inquiry into the way the Government managed the deposit guarantee scheme.
The Serious Fraud Office on Wednesday laid charges against five people involved with failed lender South Canterbury Finance over transactions totalling $1.7 billion, including $1.58 billion after entering the scheme.
SCF collapsed in August last year owing about $1.8 billion.
Because it was in the scheme, introduced to protect depositors during the international financial meltdown, the government had to bail them out with $1.7 billion of taxpayers' money.
Labour's finance spokesman David Cunliffe, a persistent critic of the way the Government managed the scheme, says there must be an inquiry into why it didn't minimise taxpayer liability.
SCF was re-admitted to the scheme before it collapsed, and the Greens say there seems to have been a complete lack of government oversight.
"The public needs to know what Treasury and the government were doing to stop alleged fraud happening while the taxpayer was underwriting SCF," the party's co-leader Russel Norman says.
"It was important to minimise any cost to the taxpayer and, on the face of it, this wasn't the case with SCF."
Dr Norman says the auditor-general reported deposits grew by 25 per cent while SCF was in the scheme and the Treasury knew taxpayer liability was increasing.
Finance Minister Bill English won't comment on the charges, saying it's a matter for the courts.
The SFO hasn't identified the individuals who have been charged.
Chief executive Adam Feeley says the charges include theft by a person in a special relationship, obtaining by deception, false statements by the promoter of a company and false accounting.
The charges carry maximum penalties of between seven and 10 years imprisonment.
Mr Feeley says the value of the alleged fraud exceeds anything in the history of white-collar crime in New Zealand.
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