Sinn Fein has accused the British government of using the arrests of three IRA members in Colombia as an excuse to delay demilitarisation in the North.
The party's MLA for Newry and Armagh, Mr Conor Murphy, said British intelligence had "hyped up" the arrests to stall moves on the dismantling of military installations across Northern Ireland.
There has been increasing pressure on Sinn Fein to explain the nature of the links between the Marxist guerrilla group, FARC, and the three republicans held in Bogota, Mr James Monaghan, Mr Martin McCauley and Mr Niall Connolly. Mr Murphy, however, claimed yesterday that accounts of what had actually happened in Colombia were "beginning to unravel".
"On Monday they talked about these people out dealing with drugs, and that proved to be bunkum. On Tuesday they talked about some video evidence, and we have yet to see any of that. And there was an attempt to try and sell one of these people as a Sinn Fein representative in Cuba, which has proved to be rubbish," Mr Murphy said.
"The people who are spinning that story are the very people who are justifying their presence and their very existence in places like this [the North]."
The Sinn Fein MLA called on the Northern Secretary, Dr John Reid, to "go back to the drawing board" on the demilitarisation issue. "The British government proposals on demilitarisation are a pathetic joke, and their presentation two weeks ago only served to undermine the peace process," he said.
"The British Secretary of State, John Reid, has to go back to the drawing board and produce a realistic package and programme for demilitarisation that is credible and will build confidence in the peace process."
While the proposed demilitarisation measures - the closure of one sangar, one base and two observation towers in south Armagh - in the two governments' package were "welcome in a small way", they were no substitute for actual demilitarisation, he insisted.
His sentiments were echoed by the party's MP for South Tyrone, Ms Michelle Gilder new, who called on the British government to "get real" on the decommissioning issue.
"Their failure to honour their commitments and obligations on this key issue is along with their latest suspension of the political institutions undermining confidence in the [Belfast] agreement," she added.
Mr Murphy said the IRA's withdrawal of proposals of a decommissioning method did not present a threat to the peace process.