Acting First Minister Arlene Foster has claimed departmental solicitors in the Office of the First and Deputy First Minister have indicated Peter Robinson has not broken any rules in the scandal involving his wife Iris.
DUP leader Mr Robinson has temporarily stepped down as First Minister after claims he failed to report his wife for obtaining loans for her toyboy lover.
Parliamentary and Assembly inquiries into the allegations are to take place at Mr Robinson's request.
Ahead of the official investigations, Mrs Foster said: "The departmental solicitors' office has already considered the allegations made in the Spotlight programme and has advised Peter Robinson that he was not in breach of the ministerial code, the pledge of office, the ministerial code of conduct of the seven principles of public life, so I think it's important to say that."
She said she was also sure the senior lawyers commissioned to investigate Mr Robinson's actions would find no evidence of wrongdoing.
"I am personally confident, my party is very confident, that this will confirm that Peter Robinson, the First Minister, acted entirely properly at all times, but let's have this (investigation) and let's have it quickly."
Political opponents questioned how he could juggle the tasks of clearing his name, caring for his family and negotiating with Sinn Fein.
The British and Irish Governments are concerned at the wider political significance of the affair, with fears that a weakened DUP may be unlikely to agree to republican demands for agreement on the transfer of policing and justice powers to the Assembly.
Republicans are keen to see progress on devolving policing and justice powers from London to Belfast as their price for remaining in government.
Deputy First Minister Martin McGuinness has sought answers on whether Assembly rules were breached after Mr Robinson failed to report his wife to the parliamentary authorities for obtaining the loans.