An area of farmland in County Louth is to be examined for the remains of Captain Robert Nairac, who was abducted and murdered by the IRA while working undercover.

It is the first search for his remains since he was shot and secretly buried in May 1977.

The search has been organised by the Independent Commission for the Location of Victims Remains (ICLVR).

It said it has “sufficient credible information” to begin a search of private land in the Faughart area near Dundalk.

Capt Nairac, 29, was abducted from a pub at Dromintee in South Armagh.

He was then taken across the Irish border to Flurry Bridge, where he was beaten and shot dead.

The location of his remains has remained a mystery.

In recent years, there has been a number of appeals for information made by the ICLVR.

It was established by the British and Irish governments in 1999 to find the Disappeared – 17 individuals murdered by republicans during the Troubles and secretly buried.

The remains of 13 victims have been found to date.

The ICLVR’S lead investigator, Jon Hill, said: “Robert Nairac is one of the highest profile Disappeared and yet his case is one in which we have had very little to go on.

“We believe that we do now have sufficient credible information to warrant a search.”

The precise location has not been disclosed.

Mr Hill added that “neither the landowner nor the tenant” have any connection to the decision to search the location.

The area is said to be less than one acre in size.

Mr Hill continued: “We are not time-limited but given the relatively small area I do not anticipate a protracted search period of many months.

“The Nairac family have been told that a search is about to commence and we will of course keep them informed of any developments.

“I am not going to put a number on the degree of confidence that we have that we will find his remains but if they are there we have the skills, ability and experience to find them.”

Mr Hill said on Monday that although the search would be on farmland, not bogland, it still presented challenges and that he would not set a timescale.

“It is on Faughart Hill, a battlefield site from the 1300s, so that presents a number of challenges to us,” he told BBC Radio Ulster’s Good Morning Ulster.

“Not least that we have had to engage with National Monuments Ireland who have been very supportive of the work we are doing, but it has meant we have had to add extra layers within our searching strategy to deal with any archaeology and perhaps even human remains that may be found that aren’t related to Robert Nairac.

“We will search until we find him or have eliminated that area.”

He said he had been in contact with Captain Nairac’s relatives and had spoken to them recently.

“The position they are in at the moment is that they don’t want to get their hopes up too high and they are quite right as well, because this is hope rather than expectation.

“It is a very difficult task that we are undertaking, even if we are in exactly the right area, it isn’t easy to find these remains – and if you are not then it is impossible.”

Mr Hill encouraged anyone who had information in relation to any of the Disappeared to come to the ICLVR in “complete confidence”.

Kenny Donaldson, director of the South East Fermanagh Foundation, said the “murder and disappearance of Captain Robert Nairac remains a talking point in almost every home across south Armagh and indeed much further afield”.

“At the heart of all of this is a grieving family who have been denied their basic right to have Robert’s remains and to progress a Christian burial,” he added.

“We pray that the new information which has come forward turns out to be credible.”

The search location is within a wider area of significant archaeological interest.

The Hill of Faughart has been identified as a 14th Century battle site.

The ICLVR said it has the co-operation of the National Monuments Service.

The commission has previously dismissed rumours that Capt Nairac’s body was disposed of in a meat processing plant.

It also described claims he had been involved in a number of terrorists incidents, such as the Dublin and Monaghan bombings, as “wild allegations”.