Allied Irish Bank has confirmed that some of its business users have not been able to access its online systems for more than 24 hours.

However, the bank said its internet banking service was working “for the majority” of its customers.

Users of the service contacted this newspaper to complain that they were being denied access to their accounts and were as a result unable to make transfers and payments.

When contacted, the company said it was experiencing “an intermittent issue which has caused delays for some customers accessing the service”. A spokeswoman said no payments or transfers would have to be missed and said any users experiencing difficulties needed to repeat the processes.

She did not give any indication as to what was behind the problems but said the company was “working on a resolution”.

A message on the business banking website “sincerely” apologised for any inconvenience caused and said that bank appreciated customers patience “while this matter is being addressed”.