RTÉ News has learned that the chairman of the decommissioning body, General John de Chastelain, will meet representatives of the Irish and British governments tomorrow to tell them that full decommissioning of IRA weapons has taken place.
General de Chastelain will present a detailed inventory of decommissioned weapons to the British and Irish governments before making the list available at a news conference.
Two independent witnesses will make a statement at the press conference to say that the promised IRA move has taken place.
It is understood the two witnesses are the Catholic priest Fr Alex Reid and Rev Harold Good, a Methodist minister.
The IRA arsenal is believed to include Soviet-built surface to air missiles, rocket launchers, heavy machine guns, armour-piercing sniper rifles, three tonnes of Semtex, about 1,000 Kalashnikov AK47 assault rifles and large quantities of handguns.
Both governments will make statements tomorrow following General de Chastelain's statement.
Sinn Féin Chief Negotiator, Martin McGuinness, has said he believes that Ireland stands on the cusp of a historic advance.
He said he was confident that tomorrow would bring the final chapter on the issue of IRA arms.
Mr McGuinness also said the IRA move will place a huge responsibility on the leadership of the DUP to re-engage in the political process and on the two governments to implement the Good Friday Agreement.
In July, The IRA called an end to its armed campaign and ordered all its units to dump arms.
It also ordered its members not to engage in any other activities of any kind.