The DUP says an independent investigation has cleared Iris Robinson and Castlereagh council of any wrongdoing in the awarding of a contract to her former teenage lover.
A report on the investigation was presented to councillors on Thursday.
It examined whether councillors and officials complied with legislation and if any impropriety took place.
DUP MLA Jimmy Spratt said the report made "absolutely no criticism whatsoever" of Mrs Robinson.
He also said the report made no criticism of any councillor or council official.
Mr Spratt said: "Those who previously engaged in rumour-mongering and mud-slinging now have no foundation to continue to do so.
"There is no evidence of wrongdoing by officers of the council or either past or present councillors within the council in Castlereagh."
Representatives from Deloitte, the consultants who carried out the investigation, presented an executive summary of the draft report to councillors.
The findings have not been publicly circulated.
A statement by Castlereagh council said: "The report concluded that there was no evidence of financial loss to the council or any impropriety by council officers or members directly involved in the assessment panel regarding the award of the lease.
"As the final draft report has only been received this evening, the council will require time to comprehensively review the report and enable councillors and officers to respond to the content," the statement said.
The council commissioned Deloitte to undertake the independent internal investigation following allegations broadcast in January 2010 on a BBC Spotlight programme.
The programme alleged she acted illegally over money deals connected to the Lock Keeper's Inn, a cafe on the banks of the River Lagan in Belfast, run by her lover Kirk McCambley.
Mrs Robinson resigned as an MP, MLA and councillor, amid controversy surrounding the programme.
In March 2011, the Public Prosecution Service said that "following careful consideration of all the available evidence, a decision has been taken not to prosecute in this case".
The BBC issued a statement in response to the Deloitte report.
"The BBC stands by its journalism. We believe that the issues Spotlight uncovered during its investigation of several months into Iris Robinson were of significant public interest and were well sourced," the statement said.
"The BBC conducts its investigations in compliance with strict editorial guidelines. This programme was a piece of responsible journalism and a matter of public importance."