DUP leader the Rev Ian Paisley has warned the British government that "propaganda" will not ease unionist concerns about any imminent act of IRA decommissioning.
He said both governments knew what was required before political progress involving Sinn Féin was possible and warned them against fudging the issue.
"This matter is very serious," he said. "When the two governments published the comprehensive agreement they made it very clear what was required of Sinn Féin/IRA. It is quite evident from what Sinn Féin/IRA said yesterday that this is not now the position.
"There were to be witnesses, photographs and very clear transparent acts of decommissioning," he continued.
"Now if we want a unionist observer, that observer can only be considered if I, as the spokesman for the majority of unionists, request such an observer.
"Mr Adams has made it clear that he would then consult with his colleagues in the IRA and it would rest with them whether they would permit such an independent unionist observer. He also made it clear that the IRA would not be favourable to any request I would make. This is not acceptable."
He put to the British government a direct question: "Will unionist demands for open, verifiable, photographed and witnessed decommissioning be adhered to or not? Furthermore is that what the British government has requested of the IRA, and have they made it clear to the IRA that nothing else is satisfactory?"
Dr Paisley said unionists had a right to pose the question and to expect a straight answer.
"Unionists are not going to be pushed over by the duplicity of either the IRA or the two governments. We have a right to know the truth. The day for deception is over, the day for the truth, the whole truth and nothing but the truth has come. A large propaganda campaign by the government to sell the diluted form of decommissioning agreed with the IRA will not relieve the situation."
Eddie McGrady of the SDLP pressed the IRA to decommission fully and quickly, claiming that delaying the move would further damage the Good Friday agreement. The South Down MP added: "Martin McGuinness now says that decommissioning is a challenge to unionism. The SDLP has always said that.
"Perhaps Martin McGuinness will now also accept that the delay gave anti-agreement unionists just the excuse that they wanted and gave pro-agreement unionists a loss of nerve," Mr McGrady said.
He claimed that "Provisional activity like the Northern Bank raid, the 'Colombia Three' and the McCartney murder" had undermined politics. However, speedy, transparent decommissioning was one way they could help rebuild confidence.
"The Provisional movement used to say decommissioning was a red herring and would never happen. They used to condemn us when we said decommissioning had to happen under the Good Friday agreement, and that it eventually would happen.
"Now the red herring is the latest historic, seismic breakthrough."
Sir Reg Empey, the Ulster Unionist leader, claimed that any republican decommission was a direct result of pressure from his party.
"We must remember that the republican position used to be 'not a bullet, not an ounce'. They have now been forced to admit that their illegal weapons should be decommissioned," he added.
"Nationalists should realise that the launch of the Make Partition History campaign is a deliberate attempt by republicans to create a smokescreen for their retreat on arms."