Minister for Social Affairs Séamus Brennan is to meet Siptu leaders tomorrow to hear complaints of "large-scale abuse" of the construction industry pension scheme.
The union claims up to 50 per cent of building workers are not covered by the scheme because of the failure of "cowboy employers" to make contributions, which are compulsory.
The Construction Industry Federation (CIF) accepts there is some abuse of the scheme, but says progress is being made.
Mr Brennan invited Siptu representatives to meet him tomorrow following a protest outside his Dublin office by the union last week. It wants the Minister to introduce a centralised collection system for pension contributions by builders.
The scheme concerned, the Construction Federation Operatives Pension Scheme (CFOPS), was set up in 1965.
Under a legally-binding registered employment agreement (REA), construction companies are required to make pension contributions to the scheme for all general workers and trades people over the age of 20.
Siptu construction branch secretary Eric Fleming said millions of euro were being withheld from the scheme because of the failure of a large number of employers to make mandatory contributions. As a result, thousands of workers were being denied their rights to pension, sick-pay and death-in-service benefit. "Every day our union gets complaints from workers about pensions abuse. The Minister has it in his power to stamp out this abuse.
"If he is serious about the provision of pensions to all workers in the industry then his department could conceivably get another 60,000 workers into membership of the scheme just by getting directly involved in the central collection of building workers' pension contributions."
Mr Brennan said he had no direct responsibility for the scheme, but he was anxious to ensure the law was complied with, and that members' contributions and benefits were secure.
As well as inviting Siptu to a meeting to discuss its concerns, he would ensure that the Pensions Board continued its comprehensive review of the scheme.
An examination of the scheme by consultants hired by the board is due to be completed within months.
The CIF said a review of the scheme in 2002 had led to major improvements, including enhanced funding and benefits for workers on retirement.
It said about 90,000 workers were eligible to be registered in the scheme, but only about 70,000 workers were covered.
The CIF had agreed procedures with trade unions on how best to tackle the issue.
"Five years ago there were about 37,000 workers in the pension scheme. Today the number is just over 70,000 workers and increasing."