The Labour Party will debate Iraq later today, a day after British Prime Minister Mr Tony Blair used his address to strongly defend the decision to go to war.
The Rail, Maritime and Transport union was due to challenge a decision by the conference organisers to rule out of order their emergency motion questioning the justification of the war in the light of the failure by the US/UK coalition to find any weapons of mass destruction.
Conference organisers have timetabled a debate and vote on Iraq but the union believed it would be on an uncontroversial aspect of the conflict.
RMT general secretary Bob Crow said the public was "clearly against the reasons for the war".
He told BBC Radio 4's Todayprogramme: "The Liberals have debated it, the Scottish Nationalist Party has debated it, the Tories will debate it next week. "All we are voting on today is the actual policy document about the restructuring of Iraq which is a totally different issue. I think everyone wants Iraq reconstructed.
"What we want to know is, was it actually right to go to war? That is what our resolution is about, saying quite clearly it was wrong for the British Government to go to war, and we had no authority."
Iraq was sure to feature in the afternoon's debate on Britain's place in the world, which will feature speeches by Foreign Secretary Jack Straw, International Development Secretary Baroness Amos and Defence Secretary Geoff Hoon, who faced tough questioning during the Hutton Inquiry into the apparent suicide of Government weapons expert Dr David Kelly.
Despite Mr Blair's insistence in his own speech to conference yesterday that he would take the same decision again on Iraq, the Prime Minister faces continuing opposition from within the Labour ranks.