Two of the country's biggest rail workers' unions, including one led by left-winger Bob Crow, have started talks aimed at a merger.
The RMT and TSSA said that initial discussions will focus on closer ties with a view to moving towards a merger.
They added that other smaller specialist unions in which may be thinking along similar lines would be able to join the discussions at a future date.
COMMENT RULES: Comments that are judged to be defamatory, abusive or in bad taste are not acceptable and contributors who consistently fall below certain criteria will be permanently blacklisted. The moderator will not enter into debate with individual contributors and the moderator’s decision is final. It is Belfast Telegraph policy to close comments on court cases, tribunals and active legal investigations. We may also close comments on articles which are being targeted for abuse. Problems with commenting? email@example.com