Ulster Bank customers hit by the month-long IT meltdown which crippled the bank are to be offered a one-off compensation payment and free banking for three months.

Under the package, worth at least 35 million euro (£28 million), the bank will give 25 euro to personal current account holders in the Republic of Ireland and £20 to Northern Ireland customers.

The offer is open to anyone forced to use branch banking more often than normal during the four-week data chaos. Ulster Bank also vowed to waive certain fees, charges and surcharge interest for three months as it bids to rebuild its reputation among its 600,000 customers.

Chief executive Jim Brown said: "We recognise that we have work to do to restore our customers' trust in us and we believe that this is the first step in that direction. We have worked with our key stakeholders to ensure the additional measures which we are taking provide a comprehensive response to customer concerns and demonstrate our commitment to making amends."

Ulster Bank said it was offering the payment to cover inconvenience caused during the IT crisis between June 19 and July 18.

Customers are also being urged to claim from the bank for reasonable out-of-pocket expenses incurred during the technical chaos. The bank said it will start processing claims from Monday, with personal and small business customers in the Republic also offered a top-up 20% up to a maximum payout of 120 euro and £100 for Northern Ireland customers. It has urged customers to back up claims with paperwork such as phone bills, bus tickets, travel receipts, bills or invoices.

For customers with savings on deposit, the bank has also offered a one-off payment. It will be the equivalent of an additional rate for three months of 0.06% gross, 0.25% on the average daily balance, between September 1 and November 30 this year. It will be automatic and applies to personal banking and small business customers with a savings account. Ulster Bank said any errors made on fees, charges and debit interest will be corrected by the end of October.

Amid fears that the banking breakdown will damage customers' credit rating, free financial health checks are being offered from the Irish Credit Bureau. Reports on ratings will be available within five days for customers who have any concerns.

Ireland's Central Bank said investigations into how the technical failure at Ulster Bank and the wider RBS Group emerged and developed are continuing.

And customers in the UK and Ireland have been urged to approach the Financial Ombudsman if they fail to get satisfaction over losses. In the UK, the Consumer Council said bank customers may qualify for compensation for more than just financial loss. "We have guidance on the types of things people can claim for which include losses which aren't financial, such as trouble, stress and inconvenience," it said.