The State could face an additional pensions bill of around €360 million each year from public servants if retired RTÉ workers succeed in changing State pension arrangements, an Oireachtas committee has heard.

The RTÉ Pensioners' Association wants its members who have paid reduced social insurance rates over their years of employment to receive the full contributory old age pension.

However, if implemented, the change would apply across the public sector, the Department of Social and Family Affairs said, putting an unacceptable strain on a pensions system already facing a "time bomb" as a result of a growing older population.

Currently, public sector workers who have paid the reduced or "modified" rate, are eligible for benefits such as widows' and orphans' pensions for their dependants, bereavement grants and carers' benefit.

However, they do not receive contributory old age pension payments because their occupational pension scheme is deemed adequate. Those on the modified or "D" class contributions pay 2.9 per cent of their earnings to the social insurance fund, while the full contribution or "A" class rate is 6 per cent.

The RTÉ pensioners submit that they should receive at least some pension payments for their contributions over the years.

They have asked that for every four modified contributions paid, they should be credited with one full rate contribution.

This would qualify a person who paid modified rates for 40 years for a 50 per cent pension, which, after Budget 2006, amounts to €96.50 a week.

The estimated cost to the State for the current 680 RTÉ pensioners would be around €4.2 million per annum, according to the Department of Social Welfare.

However, there are around 133,000 public sector workers, including gardaí, civil servants, the defence forces and teachers, insured at modified rates and the proposed change could result in an additional €360 million annual payment, the Department said.

"Assuming that two-thirds of existing public service pensioners qualified for the scheme suggested by the RTÉ Pensions Association then the cost could be of the order of €360 million per annum and this does not include pensioners in the commercial state sector," Anne Vaughan, principal officer at the department told the Oireachtas social affairs committee.

The change would result in a "significant ongoing overhead on a pensions system which is already facing a very large increase in costs as a result of demographic changes," she said.

The RTÉ submission is being considered by the Oireachtas committee, but Ms Vaughan said it could have "widespread and costly implications" for the next 30 years.