The Central Bank has declined to comment on reports that it was misled by AIB on bad loans.

An employee of AIB reportedly contacted the Central Bank of Ireland and the ECB in Frankfurt on Wednesday, alleging the bank misled regulators about the progress it was making in dealing with loans that are in arrears.

The implication is that profits may have been overstated as a result.

It is understood the whistleblower, who contacted the banks via an anonymous email, has worked in AIB’s Financial Solutions Group where hundreds of staff have been focused on managing the bank’s bad debts.

The borrowings were for a wide range of businesses.

The ‘bad loans’ amounted to €20bn in 2013. According to the latest AIB financial results published last month, impaired loans had fallen to €13bn at the end of 2015. AIB announced a 72% increase in pre-tax profits to €1.9bn for 2015.

Close to half that figure was as a result of writing back bad debt reserves into profits, that is money that had previously been set aside in the event loans were not repaid.

AIB told RTÉ News that it is “not aware” of the allegations.

Update 2.05pm: Sinn Féin Finance spokesperson Pearse Doherty has said that the allegation must be fully investigated by the proper authorities.

“The allegation from the whistleblower today is extremely worrying and needs to be fully investigated by the proper authorities,” said Deputy Doherty.

“It is also deeply worrying that allegations such as this one seem to be continuously missed by the regulator.

“Issues such as the tracker mortgage scandal and the moneylenders scandal were brought to light by consumers and whistleblowers. Questions must be asked of the regulator about why these issues seem to continuously be missed.”