GARDA and Army personnel involved in searches for IRA arms and ammunition in Co Louth have diverted their investigation to land near Castlebellingham.
The searches began in early October and concentrated on land within a few hundred yards of the Border with Co Armagh.
On Tuesday a primed Mark VIII mortar and a pressure mat were found on farmland at Rassan, north of Hackballscross, approximately 200 yards from the Border.
The operation was later transferred to open land a mile south of Castlebellingham which is on the main Dublin to Belfast road.
Semtex explosive, detonating cord, Cortex fuses and three two way radios were found there at about 5 p.m.
A Garda representative said it was difficult to determine how long they had been concealed as they were contained in a pipe which had been buried in a ditch, and they were dry.
At the beginning of August, gardai uncovered a rocket launcher and 900 rounds of assorted ammunition in the Fane River, just a few miles north of the scene of this week's finds.
In October gardai found the first of 10 caches of explosives, bomb making equipment, firearms, ammunition and mortars on isolated farmland near the Border. All were near Hackballscross and Ballybinaby. On November 18th, a major cache of explosives and bomb making equipment was found at Ballybinaby. It included 2 kg of Semtex, 1 kg of home made explosives, rifles, pistols, mortar fuses and an array of bomb making equipment. A senior garda described it as "an Aladdin's cave of bomb making materials".
The current series of searches along the Border began after reports of noises being heard at night were given to gardai. It is believed that information received by gardai led to the searches being transferred to Castlebellingham.
Those searches are expected to continue today.