AIB lost €2 for every €1 it raised from the sale of a repossessed home last year, the Irish Independent has learned.

The bank repossessed 60 residential properties last year, selling on 17 of them – but it lost €4m in the sales.

Detailed accounts filed by its mortgage unit include never-before-seen details about the state of the bank's mortgage lending up to the beginning of this year.

It includes the fact that AIB raised €2m by selling 17 repossessed properties last year, which amounted to just a third of the debt owed on the homes.

As a result the bank was left nursing losses of €4m on the sales. The worst losses were on the so called buy-to-lets.

The bank took a €3m hit when it sold nine properties secured by buy-to-let mortgages for a combined total that amounted to just a quarter of the €4m owed on the properties. It fared better from the sale of "owner-occupied" homes. Sales of eight repossessed family homes raised €1m, exactly half the debt owed.

ARREARS

Losses from the sale of repossessed homes had been slightly lower in 2011.

Of the 60 homes repossessed by AIB last year, 37 were secured by so called "buy-to-let" mortgages and the rest were "owner-occupied" family homes.

The total number of homes repossessed was up from 16 the previous year but is just a tiny fraction of the bank's total "book" of 153,000 mortgages.

The number of repossessions looked certain to rise sharply when AIB chief executive David Duffy warned borrowers in arrears there was "no rent-free option" and said the bank had started issuing thousands of legal letters to those furthest behind on repayments.

It suggested the beginning of a surge in repossessions. However, news the bank has suffered big losses when it has managed to take control of homes indicates the surge could be far less than many analysts are predicting.

The details are contained in the 2012 financial accounts for AIB Mortgage Bank. It is part of AIB Group but has its own banking license and files separate accounts with the Companies Office to the main stock market listed parent.

The Mortgage Bank's core function is to borrow on the bond markets for AIB using its stock of home loans as collateral. The need to attract those lenders means its accounts contain very detailed breakdowns about the home loans – including the figures on repossessions.

The accounts also show that 46pc of owner-occupied homes and two-thirds of "buy-to-lets" were in negative equity at the end of last year. Those numbers mean AIB could expect to take a major financial hit if it repossesses more homes.

That tallies with a warning from ratings agency Fitch earlier this month. It said repossessions will be the final resort for banks, because negative equity means lenders may not want to crystallise losses.

Irish Independent