SIPTU is to seek the support of trade unions in eastern Europe to recruit immigrant workers in Ireland.
The initiative is aimed at reducing exploitation of immigrant workers, many of whom are afraid to approach unions for assistance, SIPTU says.
It plans to approach workers' organisations in eastern Europe and ask to them to supply, in their own language, a letter explaining the benefits of trade union membership.
The unions will also be asked to encourage migrant workers to contact SIPTU as soon as they take up a job in Ireland.
Mr Mike Jennings, SIPTU's regional secretary for the midlands and south-east, said the union had encountered numerous cases of "gross exploitation" of foreign workers in Ireland. These occurred mainly where there was no trade union representation, he said.
"Once the union won representation rights, the workers concerned enjoyed an almost immediate and total redress of their grievances in practically all cases."
"One of the major obstacles we encounter, however, is the lack of understanding by immigrant workers of the role and function of trade unions in Irish society and their fear of approaching us for assistance," he said.
This fear was "readily exploited" by unscrupulous employers, he claimed.
It was in the interest of all workers, Irish and foreign, that such cases of exploitation were stamped out, Mr Jennings said.
"To allow bad treatment to continue is not only intrinsically immoral, it will also lead inevitably to the pay and conditions of Irish workers being undermined."