The Serious Fraud Office is investigating five related party loans involving South Canterbury Finance made between 2005 and 2009.

SFO chief executive Adam Feeley said that he wasn't prepared to name the specific transactions under scrutiny for potential false statements or other fraudulent conduct, at this stage.

The Serious Fraud Office announced this morning it had launched an investigation into South Canterbury Finance.

The company went into receivership on August 31, triggering a $1.6 billion payout under the Government's deposit guarantee scheme.

"Obviously we know what they are but we don't want to get drawn into the details until we have had the opportunity to review all the documents and also talk with people, who on the face of what we've seen were part of those transactions, to understand what part they played in it and also what representations they may or may not have made," Feeley said.

Asked about the timeframe of the deals Feeley said: "The earliest goes back to 2005 and the last date I have seen is 2009."

He said that "as of today" there were five transactions under the spotlight.

The latest investigation is separate from the office's probe into the affairs of Aorangi Securities Limited.

"When I say transactions, loans, and obviously there are numerous transactions related to those loans but we are in the very early days of the investigation," said Feeley.

"We may find either none of those transactions or one of those transactions warrants further investigation, or we might find out that number doubles, trebles or quadruples."

Meanwhile, a Treasury spokesman confirmed the probe would not affect the NZ$1.25 billion payout to South Canterbury Finance debenture and deposit holders under the Crown retail deposit guarantee scheme, due to be made tonight tomorrow.

Feeley noted that the Crown guarantee required any party entering into it, or remaining in it, to disclose certain information.

"Amongst other things it required them to disclose transactions with other parties which weren't on an arms length basis," said Feeley.

"If indeed these transactions are proven to be not on an arms length basis, and had to have been disclosed, then the question may arise would South Canterbury Finance have been admitted into the scheme had it disclosed these transactions, or would it have remained in the scheme had it disclosed them?"

"As I understand - the Crown would not have suggested that the beneficiaries of the scheme - ie the investors, would ever be effectively punished by a mis-statement," said Feeley.

"But either eligibility or on-going eligibility may have terminated."

He noted that one finance company - Viaduct Capital - which initially entered into the scheme was kicked out because of related party transactions.

"Investors funds (up) to that point were guaranteed but any new investment was no longer guaranteed," said Feeley.

Meanwhile, Feeley wouldn't say where the information the SFO had acted on had come from.

The company had been monitored by KordaMentha whilst under the Crown guarantee.

"It would be fair to say the information we've got to date is from reasonably well informed sources but there will need to be further talks with parties who will be equally well informed - from (South Canterbury Finance CEO) Sandy Maier through to KordaMentha over the next few weeks," Feeley said.

Although the SFO wouldn't comment on individuals, Feeley did say there was no suggestion that Maier was implicated "in any way."

As for South Canterbury Finance's former owner Allan Hubbard, Feeley said: "We're not commenting on individuals. (But) people can draw their own conclusions about whether any one individual might be the subject of our inquiry based on the extent of involvement they had with South Canterbury Finance.

A separate SFO investigation into the affairs of Hubbard's Aorangi Securities was nearling its conclusion with a decision on whether to lay charges or close the investigation not far off. However, new information had emerged during the investigation and it was possible this could happen again, potentially delaying a decision.

"I think we're in the closing stages (of the Aorangi investigation)," said Feeley.

"It could be two or three weeks (until a decision is revealed), it could be upwards of six, but I don't think it would be longer than that," Feeley said. "But the caveat is if the goal posts shift on us then we've got to respond."

As for the South Canterbury Finance investigation, it was impossible at this stage to estimate how long it might take.