RTÉ News has learned that Permanent TSB cannot appoint receivers to take control of troubled buy-to-let properties because of an issue with the mortgage contracts which were drawn up by the bank.
It means that the lender will have to go through a lengthy courts process if it wants to repossess investment properties.
Separately, the bank has warned customers who want to sell their homes in the coming months that they face delays in disposing of their properties because of a review of mortgage contracts being carried out.
Permanent TSB has over 3,500 buy-to-let loans which are in difficulty.
Because of the issue of the mortgage contracts, the lender can not dispose of any investment properties quickly.
Instead of engaging a receiver to make a swift sale, the bank must go through the courts - a process which is costly and can take several years.
Meanwhile, the bank has confirmed that homeowners who want to sell their properties in the coming months are likely to face delays because of a review of mortgages being undertaken by the bank.
Permanent TSB says it is carrying out an assessment of all mortgage contracts to to identify any instances where the contractual terms and conditions attached to mortgages with the bank were not fully honoured.
The assessment will also identify whether customers may be entitled to compensation under a scheme set up this year.
Customers considering the sale of their property are being warned that they are likely to face delays in processing sale approvals in the coming months.
