Analysis: Mr Lauri McDonnell and his team of investigators have a mammoth task to complete over the coming weeks. Their main focus is to establish how the bank overcharged certain foreign exchange customers to the tune of €20 million over almost a decade, writes Siobhán Creaton, Finance Correspondent.

Within that investigation they will have to probe allegations that certain AIB branches systematically raised charges in the early 1990s to boost profitability. The bank's practice of automatically applying payment protection cover to some mortgage customers without their knowledge also falls within their remit.

On top of that, and perhaps the most crucial of its endeavours, comes yesterday's announcement of the widening of its brief to determine whether the bank may have overcharged customers on other services.

Mr McDonnell and the investigating accountants from Deloitte have stated that they will scrutinise all of the charges the bank had to notify to the regulator from 1996. The outcome of these investigations are expected by the end of July.

Mr McDonnell will issue three reports: one dealing with the foreign exchange overcharging, the second explaining why this happened and a third examining the bank's internal control procedures.

AIB will be hoping that this investigation will go some way towards reassuring its customers that overcharging is something that they should not have to endure in the future.

Consumers will undoubtedly look for greater assurances from the Irish Financial Services Regulatory Authority (IFSRA) in this regard. IFSRA will consider Mr McDonnell's report and will issue its own report later this summer.

It has already ordered the bank to deposit €25 million at the Central Bank and is involved in repaying the €20 million to customers who were overcharged on foreign exchange transactions together with another €5 million in interest as compensation for their loss.

IFSRA chief executive, Mr Liam O'Reilly, has publicly reminded directors and senior executives of financial institutions of their responsibilities for ensuring their organisations uphold the law.

It is expected that the regulator will consult with AIB's chairman ahead of a meeting of the bank's board of directors to consider these reports. These discussions are likely to cover how the directors should apportion blame for its wrongdoing.

Mr Gleeson and chief executive, Mr Michael Buckley, have stated that the bank will not be scapegoating junior staff this time around. Just two years ago AIB's board decided that none of the bank's senior executives should be censured for the $691 million trading fraud at the bank's US operations in Baltimore, Maryland.

There have been numerous calls for Mr Buckley's resignation, but Mr Gleeson has supported him publicly. Informed sources believe that he will not be asked to resign next month - but that his time at the helm at AIB will now be shorter. His current term is due to end in early 2006.

It will be interesting to see how AIB deals with the latest revelations. It must realise that revelations that some of its most senior executives invested monies in an offshore company that was found to have breached tax laws will not quickly fade.

Former AIB chief executive, Mr Gerry Scanlan, former deputy chief executive, the late Mr Patrick Dowling, the former director of strategy, Mr Diarmuid Moore and Mr David Cronin, the former AIB executive who was in charge of the bank's US treasury operations at the time of the currency fraud in 2002, were all beneficiaries of a company based in the British Virgin Islands and managed by AIB Investment Managers.

Mr Roy Douglas, a former senior AIB executive who last week retired as chairman of Irish Life & Permanent, was also a beneficiary and has said that he was "invited" to join it when he reached the bank's senior ranks.

Another former AIB chief executive, Mr Tom Mulcahy, was one of five executives who had tax issues arising out of another unconnected scheme. Three of the other participants still work for the bank and are facing a disciplinary process.

Mr Douglas has claimed that these type of schemes were offered as a type of perk and had been in place for a long time. AIB has said that it has completed its investigation into these practices which began in 1989. One question is whether IFSRA will now look at what went on before 1989.