The Serious Fraud Office has announced it will not press charges against the Blue Chip group of companies, citing a lack of evidence.

The SFO said today it had launched an investigation into failed finance company Dominion Finance and sister company North South Finance, but has decided not to press charges against another failed investment company, Blue Chip.

SFO chief executive Adam Feeley said the office had completed its investigations into the Blue Chip group of companies, but that investigations would continue in relation to one of its South Island franchises.

Feeley said the decision not to prosecute Blue Chip was not made lightly.

"The Blue Chip investigation has attracted intense public and media interest. However, in order to lay criminal charges there must be a reasonable prospect, based on credible evidence which could be admitted in Court, that an impartial jury could be satisfied, beyond reasonable doubt, that the person prosecuted has committed a criminal offence."

"We have concluded that this evidential threshold cannot be met."

The matter could be reviewed if further evidence came to light, Feeley said.

Feeley said the SFO had also referred matters of professional conduct of lawyers involved in the Blue Chip developments to the NZ Law Society for inquiry.

Meanwhile the investigation into Dominion and North South Finance involved a number of related party transactions undertaken prior to both companies' collapse in 2008.

The matter had been the subject of an extensive preliminary inquiry prior to commencing a formal investigation, Feeley said.

"We have concluded a number of cases which now enable us to address issues identified in the preliminary inquiry," he said.

The Serious Fraud Office had already worked closely with the Securities Commission in relation to the matter.

In July this year the Securities Commission laid criminal charges and issued civil proceedings under the Securities Act against former Dominion Finance Group Limited and North South Finance Limited directors

The Serious Fraud Office is investigating 22 matters against companies including Nathans Finance, Capital + Merchant Finance, Aorangi Securities, Belgrave Finance and South Canterbury Finance.