The State's two biggest trade unions said yesterday they would pool resources as part of a co-operation agreement to be concluded by May 1st.
But SIPTU and IMPACT said they were not considering a merger of the two organisations, which between them represent almost 50 per cent of union members. Instead, they will engage in a series of joint projects such as recruitment strategies and co-operation in workplaces where they both have members.
The move carries added significance given the bad feeling that had existed between the two unions as a result of the defection of more than 1,000 Aer Lingus cabin crew from SIPTU to IMPACT five years ago.
At the time, the chairwoman of the cabin crew committee involved, Ms Nora O'Reilly, told SIPTU: "The divorce is final, you can keep the cat."
In a joint statement yesterday, both unions said they recognised that co-operation was the best way to secure membership growth.
SIPTU president Mr Jack O'Connor said the agreement would formalise an already constructive relationship between the two.
The unions plan to co-operate in research, information and education and to work together at local level to maximise the influence of trades councils. They say they will also exchange views and experiences on best practice in recruiting unorganised workers into unions.
IMPACT general secretary Mr Peter McLoone said the initiative would help both unions to grow and bring benefits to thousands of workers.
SIPTU has more than 200,000 members, about 135,000 of whom work in the private sector. IMPACT has 54,000 members, most in the public sector.