The council is to look into Iris Robinson's behaviour as a councillor
Castlereagh council has voted to hold an external investigation into its decision to award a catering contract to Iris Robinson's teenage lover.
The council wants the inquiry to examine whether it suffered financial loss by awarding the lease for the Lock Keepers Inn to Kirk McCambley.
Mrs Robinson procured money from two developers to help him open the cafe.
She then attended a council meeting when the lease was awarded and broke the law by not declaring an interest.
Investigators will be also be asked to ascertain whether or not council officers and members complied with local government legislation and to examine if any impropriety took place.
The decision to agree the terms of reference was endorsed unanimously by councillors at Wednesday night's meeting.
It is expected that the council will shortly announce who will carry out the investigation and give some indication as to how long the inquiry will take.
Meanwhile, it has been confirmed that Mrs Robinson has resigned as an MP, MLA and councillor.
The Speaker of the Northern Ireland Assembly told the BBC that her decision would be formally announced to MLAs next Monday.
INQUIRY TERMS OF REFERENCE
To identify if the council incurred any financial loss as a result of the award of the lease at the Lock-Keeper's Inn
To investigate any impropriety on the part of the officer and elected representatives in the award of the lease at the Lock-Keeper's Inn
To investigate whether officers and elected representatives complied with the requirements of all relevant local government legislation and guidance in the awarding of the above-mentioned lease
To make any recommendations to the Council, where necessary, arising from the findings of the investigation on how its processes and governance arrangements could be improved upon
Revise these terms, where necessary, arising from the findings of the investigation
Earlier on Tuesday, the Treasury announced that Mrs Robinson had formally announced her resignation as MP for Strangford. Her resignation from the council was announced by its acting chief executive.
Mrs Robinson has applied for the Chiltern Hundreds, the system used by MPs who wish to resign.
At the weekend, the DUP said that Mrs Robinson was leaving the party.
Last month, she issued a statement saying she was leaving politics due to ill health; however, news that she was stepping down came earlier than expected.
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.
The programme reported that Mrs Robinson then sought to provide Mr McCambley with capital to open the business.
She obtained a total of £50,000 from two developers, Fred Fraser, now deceased, and Ken Campbell to fund the project.
Spotlight reported that while Mrs Robinson was asking Mr Campbell for the money, she also lobbied on his behalf for one of his building projects in her former parliamentary constituency.
Mr McCambley said he received two cheques, which he invested in kitchen equipment and furniture.
He also told the programme that after he received the money Mrs Robinson had then asked him to give her £5,000 in cash.
Spotlight reported that in July 2008, six weeks after Castlereagh Borough Council advertised for expressions of interest in the cafe project, only one applicant met the criteria - Mr McCambley.
The deal was sealed on 28 August and Iris Robinson was in attendance as the council authorised the signing of the lease.
The laws covering local government state that once Mrs Robinson had a financial interest in the business, she was obliged to declare it at any meeting she attended where it was being considered. She failed to do so.
Spotlight reported that she also broke a cluster of other rules in the Code of Conduct for councillors - as many as five elements of the code.