The council is to look into Iris Robinson's behaviour as a councillor
Castlereagh Council will meet later to decide on the terms of its inquiry into the conduct of Iris Robinson.
Mrs Robinson, who is a councillor, MP and MLA, procured money from two property developers to help her teenage lover Kirk McCambley to open a cafe.
She then attended the council meeting during which the cafe lease was awarded to Mr McCambley but broke the law by not declaring her financial interest.
Cllr Michael Copeland said the inquiry should be independent and transparent.
Details of Mrs Robinson's financial and personal relationship with Mr McCambley, who runs the Lock Keeper's Inn cafe in south Belfast, were revealed in a BBC Spotlight programme last week.
'Establish the truth'
ROBINSON STORY SO FAR
6 January: Peter Robinson says his wife Iris tried to take her own life last March after admitting an affair with teenager Kirk McCambley
7 January: BBC's Spotlight reveals details of Iris Robinson's financial affairs - she obtained £50,000 from two property developers to help her lover launch a café and asked him for £5,000 for herself
10 January: DUP says Iris Robinson is receiving acute psychiatric treatment
11 January: Peter Robinson steps aside from his role as first minister for a six-week period - DUP colleague Arlene Foster becomes acting first minister amid renewed focus on resolving her party's problems with Stormont power-sharing colleagues Sinn Fein
Mr Copeland, who will chair Wednesday's night's council meeting, said that anyone who had watched the programme "could only conclude that Castlereagh must be seen in an open, transparent way to subject itself to investigation by an independent, outside body".
The UUP councillor added that an inquiry was needed "to primary establish the truth, to examine the processes that Castlereagh Borough Council went through during the events referred to in the television programme and to rebuild the trust that is necessary between people who represent the electorate in bodies such as councils".
He described that trust as "the basis and foundation of our democracy".
Mr Copeland explained that councillors were expected to discuss the identity of the individuals or body which will conduct the investigation and set the terms of reference to which they must adhere.
He also said that the inquiry would have "financial implications for the people of Castlereagh" but said the issue was "of such importance that getting at the truth will be the primary objective".
The Alliance party group on Castlereagh Borough Council have already written to Northern Ireland's main public spending watchdog, the Comptroller and Auditor General, to ask for a full and independent inquiry.