THE mortar found in Donegal yesterday by gardai was primed and ready to be used, most probably against an RUC or British army vehicle, according to senior Garda sources.
Six men, five from Derry and one from Donegal, arrested yesterday by gardai are due to appear before the Special Criminal Court in Dublin later today.
The five Derry men, aged in their 30s and 40s, were arrested in an isolated farmshed at 1.30 am. yesterday near Malin Head, the most northerly point of Ireland, by a large team of armed detectives.
Two Kalashnikov AK47 assault rifles were found in the farm buildings and a quantity of assorted ammunition.
Gardai had carefully planned the operation and the detectives were backed up by a substantial number of other armed officers in the roads and fields around the farm at Ballygorman, north of Carndonagh.
The six were arrested under Section 30 of the Offences Against the State Act and were being held last night at Burnfoot, Buncrana and Letterkenny Garda stations.
The first arrests were made by two armed detectives who entered a shed, one of a number of buildings on a farm on the Inishowen peninsula. During a follow up search of the farm buildings, the owner of the farm was detained and brought to Letterkenny Garda station.
Gardai said the five men from Derry were known to them and had come to their notice before. The Donegal man is understood to be a local farmer.
After making the arrests the gardai found the primed rocket known as a propelled rocket improvised grenade (PRIG) which is also known as a horizontal mortar.
The device is of a type which has been manufactured by the IRA and was used in Northern Ireland against security forces vehicles and caused several deaths before the August 1994 ceasefire.
The device is prepared in advance, primed and usually hidden in a rural roadside. It is fired by remote control when the security forces vehicle is driving past.
The weapon, based on the design of a former Soviet bloc horizontal mortar known as a Sagger, was first used in the south Derry area around six years ago.
Senior gardai last night felt the discovery indicated that there were ongoing preparations for attacks in Northern Ireland despite hopes for a renewed ceasefire.
It is the second significant mortar seizure by gardai in recent times. Three weeks ago, gardai in Co Louth discovered a cache of Mark 6 mortars, similar to the type used to attack Heathrow Airport in 1994, in a farm at Hackballscross, near the Border with south Armagh.
The Garda operation is the latest in a series of security forces successes in the State and in Britain since the IRA called off its ceasefire on February 8th last.
However, this did not deter the IRA from launching last month's double bomb attack on the British army headquarters in Northern Ireland which killed one soldier and injured 20 other soldiers and civilians.
The gardai in Donegal have a good record of arms discoveries, with tonnes of explosives and weapons being found in in the county. In the four years before the IRA ceasefire, only one member of the security forces was killed by the IRA in the Derry area.
Although the scene of the arms find is in a remote area of the Inishowen peninsula, it is a location that has been used in the past by the IRA. One of the single biggest arms finds was made at Five Finger Strand in January 1988 about five miles from the scene of yesterday's find. It was the first major find of Libyan supplied weapons and included 100 rifles and more than 100lb of Semtex plastic explosives.
Chief Supt Denis Fitzpatrick of the Donegal division described the find and arrests as significant and said: "Anything in relation to the IRA where we can frustrate or hinder their activity is significant."
He said the Garda was in contact with the RUC about the arrests and arms find as part of continuing liaison.