Ulster Bank customers are being warned to watch out for bogus emails from fraudsters trying to gain access to their bank details.
The warning comes as the major technical problem at the bank now enters its 16th day.
Officials at Ulster Bank say they anticipate all services will be back to normal by July 16, but the Central Bank said that it wants to hold its own investigation into the debacle.
Ulster Bank says customers will be compensated for the disruption, as will non-Ulster bank account holders, who were inconvenienced by the knock-on effects of the issue.
Representatives from Ulster Bank will appear before an Oireachtas Committee on Finance later this afternoon.
CMC senior markets strategist Brenda Kelly said that the bank now faces fresh problems with fraudsters.
"What they are kind of concerned about … are the email scams that are taking place at the moment where you'd have some customers that are being targeted by fraudsters following this calamity," she said.
"So you're getting these phishing emails claiming to be security upgrades and asking people for account details, and then of course you have some people who are pretty much taking advantage of the situation where there haven't been any problems with their [the customers] account but they [the fraudsters] are saying that there are."