The introduction of a new computer system in the Department of Social and Family Affairs has led to delays in pensions being paid.
The delays were criticised by Labour 's Willie Penrose who said a backlog of 12,000 pension applicants had built up in the Department.
"These are people who have recently retired, and who therefore no longer have an income", Mr Penrose said.
"They were, quite reasonably, expecting their pension to kick in as soon their days of retirement began. Instead they have been told they will have to wait three months before they receive a penny. Does the Department expect these people to live on fresh air in the mean time?" he added.
A spokeswoman for the Department said that not all of the pensions of applicants in the system were delayed as the department recommends applications are sent in three months in advance.
"At this point there is a total of upwards of 10,000 new claims awaiting processing. It is likely that many of these claims are advance claims from persons who have not yet reached pension age," she added.
However, the department did admit "there have been some teething troubles, which has led to a temporary build-up of new claims to be processed."
"The Department is currently identifying those claims where the customer has reached pension age or is within 4 weeks of pension age, and these claims will be prioritised for processing and paid within weeks," she added.
The new computer system, which has been introduced for the contributory pensions areas is part of the Department's service delivery modernisation programme. "This has involved necessary organisational change and associated training and induction for staff to the new system," the department said.
Mr Penrose was critical of the extent of the disruption caused by the new system. "Last week in the Dáil, we were told that the delays were caused by the introduction of a new computer system. It beggars belief that software designed to make the system better could actually mess it up to this extent. The process of rolling out this new technology has clearly been botched, and Minister Brennan must put his hand up and take responsibility," he said.