The IRA arms cache uncovered by gardaí in Co Donegal on Monday is believed to have been buried before the first ceasefire in 1994 and had not been touched since.
A home-made rocket, known as a PRIG (an acronym for propelled rocket improvised grenade), was in dangerous condition. An Army ordnance team was called to the site of the discovery outside Stranorlar, Co Donegal, removed the warhead from the device and blew it up. The explosion caused a crater almost six feet deep and it is believed it contained over a pound of Semtex explosive.
The other weapons included two AK47 rifles, a Berretta sub-machine gun, two shotguns, some detonating cord, detonators and ammunition. All the weapons were in poor condition but were usable, the sources said.
Supt Jim Gallagher said the find resulted from "intelligence information" and there was an ongoing investigation as to whether the arms belonged to the Provisional IRA or dissident republicans. Tests will be carried out on the weapons to trace their history.
"Evidence would suggest that they were there for quite a time. The guns were in serviceable condition but were in need of oiling. And there was no evidence to suggest any traffic or activity in the area recently," Supt Gallagher said.
Supt Gallagher said while the dissident "Real IRA" has a unit operating in Donegal, he didn't believe there were any more than about six members. The local detective branch was very much focused on their activities, he said.
According to Garda sources the IRA in some areas is now beginning to want to dispose of weapons, particularly the home-made rockets made in large numbers in the 1980s and 1990s.
The home-made rockets containing Semtex are becoming dangerous and it is understood the IRA also does not want its weapons falling into the hands of dissidents from either the "Real" or "Continuity" IRA groups.
The IRA is still believed to have a large arsenal of weapons, despite its highly publicised act of decommissioning last year. It is believed that an assortment of military material was destroyed at two dumps in the Border area, overseen by the Chairman of the International Independent Commission on Decommissioning General de Chastelain last October.
Garda sources report that the IRA has kept its organisation intact. It was responsible for last week's murder of a Co Down man, Mr Matthew Burns (26), who was shot dead with a military assault shotgun as he drove his car near Castlewellan. Mr Burns was a suspected drug dealer.
There are also suspicions that the IRA was responsible for the murder of two men, one of whom was facing drugs charges, in south-west Dublin earlier this year.