The Office Ombudsman is investigating a complaint of a conflict of interest in the Securities Commission's recommendation to place Timaru financier Alan Hubbard in statutory management.
The Serious Fraud Office is investigating Mr Hubbard and several of his companies and charitable trusts.
Supporters of Mr Hubbard complained to the Ombudsman's Office that a brother of a commissioner had his company placed in receivership by South Canterbury Finance in 2009.
Mr Hubbard was chairman of South Canterbury Finance at the time.
His supporters say commission member Simon Botherway declared a potential conflict of interest only after Minister of Commerce Simon Power acted on the commission's recommendation.
The Ombudsman's Office has written to the Securities Commission asking for a report and for all relevant information relating to the complaint.
Mr Hubbard and his wife Margaret were placed under statutory management on 20 June, along with Aorangi Securities and several other trusts.
Hubbard Churcher Trust Management and Forresters Nominee Company were also put into statutory management on Monday afternoon.
South Canterbury Finance, owned by Mr Hubbard, was put in receivership on 31 August owing about $1.6 billion to 35,000 investors.