Ulster Bank has reported a massive jump in operating losses to almost €361m for the first half of this year.
It compares to losses of just under €10m for the same period last year.
The bank has impaired loans worth €600m on its books, a three-fold increase on a year ago.
Ulster Bank's parent, Royal Bank of Scotland, is currently seeking to take control of the Arnotts Department Store, which has heavy borrowings from the bank.
Ulster Bank was a well-known lender to property developers.
Its now defunct First Active brand was the first to introduce 100% mortgages back in 2005.
Today, it says it has seen a significant deterioration in its financial performance in recent times.
Even though the day-to-day business is in profit, that is all wiped out due to the volume of property lending it is worried will have to be written off.
The bank said that economic conditions remain challenging with continued pressure on property prices, which is hitting the credit quality of its customers.
However, the banks said it managed to increase customer numbers by 49,000, or 3%.
Meanwhile, RBS has announced a £9m profit for the first half of 2010, compared with a £1.04bn loss last year.