BANK of Ireland has been carrying out research on ways to get homeowners to give up their valuable tracker mortgages.
The revelation has provoked a storm of protest, with the bank being accused of "dirty tricks".
Central Bank rules mean banks are supposed to act in the best interests of consumers, but a Government TD and consumer groups claim the bank is trying to find ways to trick people out of trackers.
A copy of the research has been seen by the Irish Independent.
Carried out by Red C, the objective of the research is to produce findings that would "encourage tracker mortgage holders to move off their product".
This would "ultimately improve the overall profitability of the Bank of Ireland mortgage book", the study states.
But in a finding that is a major challenge for the bank, the research found that homeowners with trackers are very attached to them and understand that they are the best-value mortgages in the market.
A customer with a €200,000 home loan who is currently being charged 2pc interest on a tracker deal would pay an extra €4,800 a year if they switched to a 4.5pc fixed-rate mortgage.
Bank of Ireland's tracker rate ranges from 1.75pc to 2.75pc.
And there is a strong prospect that tracker holders with all banks are set to be big winners with a new cut in eurozone interest rates expected as early as next month.
This could mean savings of up to €444 a year for someone on a €300,000 tracker.
In contrast to this, Bank of Ireland boss Richie Boucher refused to rule out a new hike in variable rates when he presented financial results for the bank last month.
The Red C research shows that Bank of Ireland has around one in five of all tracker loans in the market. This would indicate it has close to 80,000 residential mortgage holders on trackers.
The research involves a detailed series of questions put to 500 homeowners who have trackers to see how well they understand the value of a tracker, and questions on what it would take to get them to give up the product.
One of the key questions was an attempt to see how many people did not understand how a tracker works.
Labour TD Kevin Humphreys said he was concerned that the bank was engaged in "dirty tricks". He had requested the research from the bank after Mr Boucher referred to it when he appeared before the Oireachtas Finance Committee last November.
Mr Humphreys said the research showed the bank was only interested in its own profitability and was not acting in the best interests of its customers.
He accused the bank of conducting the research to find ways to trick people into giving up good-value trackers.
The head of the Consumers' Association, Dermott Jewell, called for closer regulation of the banking system to ensure consumers were not duped in any way by profit-seeking banks.
A spokeswoman for the bank admitted the document used blunt language and showed the bank up in a bad light. But she insisted this was because the research was only for internal use.
There was no attempt to trick people out of their good-value trackers, the bank said. Bank of Ireland was merely trying to find ways to ensure that having a tracker would not be an impediment for those who wanted to move house.
The bank was exploring if it would allow those moving house to keep part of the mortgage on the new property on the old tracker rate, with the rest on a variable rate or fixed rate.
The Red C poll found mortgage holders generally have a good understanding of the value of a tracker. Most people see the low interest rate as the biggest attraction. Just 15pc of mortgage holders do not understand the product.
The loss of a tracker is one of the big reasons people would be reluctant to move house.
However, there is a fear that European Central Bank interest rates will rise over the next five years, according to the research.
Some seven out of 10 tracker mortgage holders find making monthly payments a strain. And four out of 10 of those surveyed in the tracker survey are in negative equity.
A spokeswoman for Bank of Ireland said the bank "regularly conducts research to assess customer sentiment in order to deliver a solid understanding of our customers' needs – this is sound business practice".