95% are connected to customers who are not communicating with the bank, and who's properties are on the brink of repossession
Ulster Bank will sell 900 owner occupier mortgages which are in long-term arrears.
It will begin selling these loans, which are valued at €875m, as part of a larger sell-off of distressed loans.
How these mortgage holders and their properties will be dealt with will be up to the buyers of the loans - the bank says that customer's existing rights will be transferred with the loans.
95% of the mortgages are at least two years in arrears, and the owners are not currently engaging with the bank.
The 900 loans represent 0.5% of the bank's mortgage book in the Republic of Ireland.
Bundles like this are generally sought after by foreign funds and bought at substantial discounts.
The total loan portfolio has a face value of €2.5bn. Just under two-thirds of the set is comprised of business loans.
An Ulster Bank spokesperson said: "Ulster Bank has confirmed a significant impaired loan portfolio sale enabling the bank to strengthen its balance sheet for the benefit of its customers and much-needed competition in the banking market.
"The loans involved do not belong to typical customers, they are all in Ulster Bank’s problem debt management unit and in arrears or under specialist management for a significant period of time."