Business Opinion: Over the next few weeks the reports of the High Court inspectors into National Irish Bank will be published. It will be an event of more than passing interest to AIB and to the wider financial sector.

The investigation into NIB has been going on for six years now, during which time the bank has been effectively "stuck", unable to either attract a buyer or go on the expansion trail itself.

The danger for AIB is that it is heading into the same territory of endless inquiry and investigation, diverting management, further undermining its reputation and leaving it weakened and vulnerable.

The challenge for its board and for IFSRA, the regulator, is to plot a course that deals with the issues quickly; the difficulty for both is that any whiff of cover-up in this process just will not wash.

AIB has lost control of the game in recent weeks. The foreign exchange overcharging scandal was just about manageable, though the drip-drip of other problems in dealing with customers showed the difficulty a big organisation can face once the dirt starts coming out.

However, the Faldor affair is of another scale entirely, pointing to a culture of extraordinary arrogance and scant respect for tax law at the highest levels of the organisation during the late-1980s and much of the 1990s. As one colleague of mine put it: "I wish I was paid enough to have tax issues."

Besieged by enquiries, AIB is firmly on the defensive. Clearly, a campaign has been launched to support Michael Buckley's position as chief executive.

It was surely no coincidence when the Taoiseach, Tánaiste and the company chairman Dermot Gleeson all came out with supportive comments earlier this week. However with its reputation, if not the bank itself, now firmly "in play," the bank has been able to do little but sit and watch as one revelation followed another.

In these situations, everything is seen as a "further blow" to the bank, and the cumulative impact of the revelations can become more than the sum of their parts.

For example, in recent days one former manager put a memo into the public domain from 1991 in which a senior executive was telling branches that only the proper foreign exchange rates must be applied.

The manager let it be known, and we have no reason to doubt him, that this was to end a practice where bank branches were overcharging customers for foreign exchange transactions to boost their profits.

But what we don't know is whether this was to stamp on a few isolated incidents in certain branches - in which case, being 13 years ago, it is now no big deal - or whether it was to end a practice common across the organisation, in which case it would be very significant.

Just at the moment, however, no one will give AIB the benefit of the doubt.

The bank will go on the offensive, no doubt, presumably when the report of Lauri McDonnell, the former Comptroller and Auditor General, is published. By then it will hope to have the measure of what is going to come out, not only in relation to foreign exchange charging but also the more damaging offshore accounts saga.

However, it also faces inquiries from IFSRA, from the Revenue Commissioners and from Paul Appleby, the Director of Corporate Enforcement, who has considerable powers to extend and deepen his enquiries if he sees fit, for example through seeking the appointment of an authorised officer.

There is no suggestion that Mr Appleby will find any reason to pursue such a course. However, the very possibility will cause trepidation at AIB headquarters, as this would bring AIB firmly into NIB country.

Two conflicting pressures will now come into play for the regulators, particularly IFSRA. One is to finish whatever investigations are needed relatively quickly and make sure the appropriate action is taken, in the knowledge that an extended process could damage AIB considerably further.

The old "prudential regulation" school in the Central Bank will argue for such a course and hints of this thinking can be seen in the Taoiseach's statement about the (very real) damage to the reputation of the financial sector.

The other pressure will be to look into every nook and cranny, to take apart AIB's operations in all the areas under question, in a process that would take a considerable time.

In this scenario we will have investigations tripping over each other, banking commissions and talk shops lasting well into the future.

There is a strong argument for IFSRA to lead a speedy process, but only if AIB plays ball.

And playing ball will be painful, as it will require a huge change in the culture of Irish business organisations caught in the spotlight - which is to curl up, get defensive, tell as little as possible and hope it will all pass in time.

AIB controlled the fall-out from the Rusnak affair, appointing its own investigator and avoiding pain at a high level. However, many questions remain unanswered about the latest revelations. Perhaps AIB is answering them to the investigations now under way and we will hear the full story shortly, in which case it will be to its credit.

However, if AIB is not prepared to answer them quickly and openly, then it will deserve the lengthy investigations and mud-slinging that will inevitably follow.

Irish businesses are fond of saying they admire the US model of bare-toothed capitalism.

But what they often forget is the regulatory and legal regime that goes with it, which - although it took a few years to catch up with the chicanery of the tech-boom years - has a reputation for ruthlessly cracking down on transgressors, particularly those at a high level in their corporations.

Even in this model there is now a questioning of the wider responsibilities of business, beyond the focus of growing profits and shareholder value.

Perhaps the AIB affair will lead to a similar debate here. It should certainly lead customers of all banks to realise that they are now dealing with profit-maximising organisations, not friendly bank managers trying to help them.

But first the AIB mess has to be sorted out.

Quickly.