Ulster Bank has been told to come clean about the extent of its IT problems following a second "technical glitch" in just three weeks.
Customers faced frustration yesterday after they found themselves locked out of the bank's mobile app.
The hitch -- which prevented people from logging on for over four hours -- is the latest technical problem to have beset the group, which started with a huge IT meltdown last summer.
A furious Daithi McKay, chairman of the Stormont Finance Committee, said customers were frustrated with the bank, which recently appointed Ellvena Graham as Head of Ulster Bank Northern Ireland -- specifically to look after customer relations here.
"This is the third incident involving Ulster Bank and its IT system andcustomers are not being told what these problems are or how big the IT problem is and when it will be resolved.
"Every time we think the faults have been resolved another problem arrives and that does not instil confidence in any customer."
An Ulster Bank spokesman apologised to customers who were unable to its mobile banking applications "for a short period of time".
"This problem has now been fully resolved," he said.
"No other systems were impacted and we apologise to customers for any inconvenience caused during this short disruption to service."
Clients of its parent company Royal Bank of Scotland and NatWest, which is also part of the same group, were locked out of the bank's mobile app from 7am until after 11.30am.
It is not known how many customers were affected, although both personal and business users were hit by the problems.
June 19, 2012 -- A software update that went wrong led to a computer meltdown that left millions of Ulster Bank customers unable to withdraw cash or view an up-to-date account balance.
March 6, 2013 -- Customers unable to access their accounts or withdraw money.
March 28, 2013 -- Customers unable to use mobile banking for over four hours