Visa's payment system is now said to be operating at "full capacity" following a hardware failure which affected customers across Europe yesterday.
A statement on the Visa Europe website, posted in the early hours of this morning, said: "Visa Europe's payment system is now operating at full capacity, and Visa account holders can now use Visa for any of their purchases and at ATMs, as they normally would."
The issue was not associated with any unauthorised access or cyber attack, the statement added.
Customers starting experiencing problems using their Visa debit and credit cards yesterday afternoon.
Some transactions worked while others did not because of a fault with the company’s authorisation system.
Long queues began forming outside ATMs and there were fears machines would run out of cash if the problem continued over the weekend.
Retail Ireland said the outage caused significant disruption to businesses on one of the busiest days of the week at the start of a bank holiday weekend.
Visa has apologised to customers following the incident.
The company said it "fell well short" of its goal to ensure cards work reliably at all times following problems yesterday afternoon.
Visa users complained about the issue on social media.
A Visa spokesman said last night: "Earlier today, Visa had a system failure that impacted customers across Europe.
"Our goal is to ensure all Visa cards work reliably 24 hours a day, 365 days a year.
"We fell well short of this goal today and we apologise to all of our partners and, most especially, to Visa cardholders."
AIB has said that any incorrect pending transactions showing on customers’ accounts will be rectified over the coming days.
The bank said no customers will be left out of pocket. They have advised anyone with any concerns to contact them.
Bank of Ireland said that anyone with concerns about transactions should contact the bank.
The bank said that any "knock-on" impacts are being resolved.