Two senior IRA figures, Mr Brian Keenan, who was imprisoned in England during the 1970s bombing campaign there, and Mr Padraig Wilson, who was leader of the IRA prisoners in the Maze, have been mentioned as possible interlocutors on decommissioning, according to sources close to the Stormont talks.
Both are held in considerable regard in the republican movement. Mr Keenan has been regarded in the past as one of the foremost hardliners. He is, however, said to support strongly the Sinn Fein leadership and its pursuance of a political agenda.
Mr Keenan rarely appears in public and has little involvement in Sinn Fein. At a republican rally in Co Monaghan last year he made a hardline speech against both the British and Irish governments. He lives in a heavily fortified terrace house in the Beechmount area of west Belfast.
Mr Wilson was "OC" (officer commanding) the Provisional IRA wing in the Maze Prison in recent years. He came to public notice last year when he gave an interview to a Financial Times journalist in which he said he broadly supported decommissioning. He is said to be highly respected among Northern IRA members.
The IRA has held meetings widely among its membership this week, with senior figures delegated to inform members about the progress of the talks at Stormont.
According to some republican sources, these briefings included suggestions about some form of decommissioning in return for Sinn Fein participation in the Northern Assembly, although no definite proposals were made.
The response within the IRA to the briefings is not clear yet.
However, one IRA member in Portlaoise Prison lunged at the man sent to brief the prisoners there and is reported to have been shouting "Sell-out".
According to prison sources, Liam McAuley, who is serving a term for the manslaughter of Det Garda Jerry McCabe, attempted to attack the messenger, Gerard Hanratty, an IRA prisoner who was imprisoned in Germany for attacks on British military installations. Hanratty is currently serving the remainder of his term in the Republic and was among the IRA prisoners repatriated after the signing of the Belfast Agreement.
According to the sources, another IRA man, Patrick Walsh, who is also imprisoned for the killing of Det Garda McCabe, intervened and was struck on the face. He was taken to Portlaoise Hospital where his wound was stitched. McAuley and Walsh are known as extremist figures in the IRA. Their involvement in the killing of Det Garda McCabe was at first denied by the IRA but later admitted.
Walsh is a senior figure in the IRA and led the Limerick brigade which has responsibility for storing weapons. While on the run from the gardai, he hid in a farmhouse in Co Cavan, where he was visited by senior members of Sinn Fein. McAuley, who is from Strabane, is known to be a dangerous and volatile figure. He escaped from prison in England in the early 1990s and was arrested by gardai in Dublin in 1994. Gardai objected to him receiving bail, pointing out that he was armed with a handgun when he was arrested at Connolly Station in Dublin. He was subsequently involved in the killing of Det Garda McCabe.