The Serious Fraud Office is investigating the New Zealand activities of United States funds provider, Brockstar Group.
In a statement, SFO acting chief executive Simon McArley says "there is reason to suspect that an investigation may disclose serious or complex fraud".
The SFO investigation arises out of two other SFO cases, against B’on Financial Services, a ponzi scheme operated by Jacqui and the late Michael Bradley, and Derivatek.
As reported by NBR last year, the Bradleys sent $US1.3 million to Brockstar in 2008 in return for a $US50 million loan which never arrived.
Developer Rocky Cribb also said he paid $US1.3 million to Brockstar, which is run by Californian man Brian Willis.
US company Gomirror filed a law suit in the Orange County Supreme Court in April 2011, accusing Brockstar and Mr Willis of fraud, unjust enrichment and breach of contract.
The SFO statement says B'On and Derivatek say they paid substantial sums as advanced fees in an attempt to secure loans but the loans were never received and the advance fees were not returned.
“The desire to meet these fees may have driven the conduct that was the subject of both investigations.
"It is important that we address these drivers of financial crime and in doing so prevent further losses to the New Zealand public,” Mr McArley said.
He says if the "conduct" took place overseas it might be outside New Zealand jurisdiction, but at least it could be raised with US and other agencies.
Jacqui Bradley was sentenced to seven years and five months jail when she appeared in Auckland district court last month after being found guilty of more than 70 fraud-related charges.