Labour faces legal action next month unless it bows to a trade unionist's long-running campaign to force the party to organise and field candidates in Northern Ireland.
Andy McGivern won a change to Labour's rules at the party's annual conference in October to allow supporters in the province to become members. At a meeting next month with the party's new general secretary, Matt Carter, he will demand the same rights enjoyed by members in England, Scotland and Wales.
Mr McGivern, a shop steward at Shorts aircraft factory in Belfast, said: "We must have full and meaningful membership. That means being able to elect our own candidates to stand for local councils, for the Northern Ireland Assembly elections and for Westminster." If the party refuses, he is planning to take Labour to court under human rights or race equality legislation.
He pointed out that Labour had been resisting membership as recently as July and he was confident the party would agree to field candidates in the province.
Mr McGivern argued that 13,000 trade unionists in Northern Ireland paid their political levy to the party but had no candidates to vote for in elections. He said Labour could win support from both the loyalist and nationalist communities, and claimed several politicians from other parties had privately backed a Northern Ireland Labour organisation.
"I believe that if there had been a cross-community party we wouldn't be in the situation we are in. Look at Glasgow and Liverpool - in those areas they had problems over religious backgrounds, but now all sides of the community feel they can vote Labour," he said.
Last night David Triesman, Labour's outgoing general secretary, told BBC Radio 4's PM programme that the threatened legal challenge would be "frivolous and completely foolish". He said: "The average membership of a constituency [party] in Great Britain is over 500 people. The idea that we would start running candidates with absolutely no material base on the ground to do it would be foolish."
Labour has traditionally regarded the Social and Democratic Labour Party (SDLP) as its sister organisation in Northern Ireland, but Mr McGivern's supporters argue that the SDLP is a nationalist, rather than socialist, party and therefore deters Protestant supporters.
Brid Rodgers, the SDLP deputy leader, dismissed the threat from Labour, arguing that it would follow the Tories in failing to establish an electoral foothold.