The Government is being criticised for the way it ran the Crown Retail Deposit Guarantee Scheme.
On Wednesday, the Serious Fraud Office laid 21 charges against five people connected to failed company South Canterbury Finance following a 14-month investigation.
The Timaru-based lender was placed in receivership on 31 August last year, costing taxpayers $1.8 billion in payouts under the Government scheme.
SFO chief executive Adam Feeley says the charges involve approximately $1.7 billion worth of transactions. The biggest single transaction was $1.58 billion - the amount accessed from entering the Crown Retail Deposit Guarantee Scheme.
Nearly $1.6 billion was paid to South Canterbury Finance investors under the scheme.
Auckland barrister Chris Patterson questions the payout, describing it as one of the biggest financial crimes committed against this generation.
Mr Patterson told Radio New Zealand's Morning Report programme on Thursday the investment was high risk and does not think the taxpayer should have covered potential losses of the 35,000 investors.
"When they invested the money or put deposits in South Canterbury Finance they were chasing high returns.
"With any investment comes risk, and I just don't know why those 35,000 people were able to effectively avoid the risks that they went into those transactions with, yet the New Zealand taxpayers had to pick up the tab."
Mr Patterson says it is highly unlikely anyone will have to repay money paid to South Canterbury Finance investors under the Crown Retail Deposit Guarantee Scheme.
He says unless someone is held culpable for fraud or the demise of the company, the money paid to investors is as safe as houses.
Philip Macalister runs a financial website and says there is a lot of concern about how South Canterbury Finance was able to join the guarantee scheme.
In October this year, Auditor-General Lyn Provost released a report critical of the scheme and which Mr Macalister says exposed its risks.
"They basically came to the conclusion that it wasn't run as well as it should have been, so the Government's handling of this certainly does come into question," he says.
Listen to Morning Report interview with Chris Patterson
Opposition parties want inquiry
Before this year's election, the Labour Party called for an inquiry into how the National-led Government handled South Canterbury Finance.
Finance spokesperson David Cunliffe told Radio New Zealand's Morning Report programme on Thursday that many questions still need to be answered.
"I just think that the questions of how this massive case have been handled by the Government - not by the independent regulator - just leaves so many huge questions unanswered.
"The company was allowed to keep trading for the best part of a couple of years after the Government knew it was in deep trouble. The losses mounted (and) people invested more money in it."
Mr Cunliffe says the public will want to know that the Government's systems are robust.
Green Party co-leader Russel Norman says an immediate inquiry needs to determine if money was wasted through poor decision-making, lack of oversight or inaction.
Any inquiry should also cover the use of consultants by the Treasury, he says.
Finance Minister Bill English has not been available for comment on Thursday.
Listen to Morning
Report interview with David Cunliffe