Excavations to find the bodies of people murdered and secretly buried by the IRA will only take place in future if there is a reasonable chance of success, the Irish and British governments have agreed.
Five of the 13 victims, including Belfast mother-of-10 Jean McConville, have been found since the Independent Commission for the Location of Victims' Remains was set up in 1999.
Eamon Molloy, whose remains were left in a coffin in a graveyard in Faughart, Co Louth, in May 1999, was one of only three, however, to be found directly on foot of information from the IRA.
The remains of 23-year-old Brian McKinney and 17-year-old John McClory, who were murdered in 1978, were found in Co Monaghan in September 1999, but only after an unsuccessful search in Belfast the Christmas before.
During a 2005 review of the commission's work, a forensic investigator examined all the digs carried out and spoke to IRA representatives in an attempt to see if the locations could be narrowed down.
The commission has also investigated the disappearance of Charles Armstrong and Gerard Evans, who disappeared from Co Armagh. It has also investigated the cases of SAS soldier Capt Robert Nairac and of Séamus Ruddy, thought to have been murdered in France by the INLA.
An extended search on Templetown beach in Co Louth for the body of Jean McConville, using IRA-supplied information, failed in 2002, though she was found accidentally a year later by walkers on nearby Shelling Hill beach.
Last night, the Department of Justice, Equality and Law Reform said searches were very difficult for the families and would only be undertaken in future when there was confidence that a body would be found.
Expressing "a note of extreme caution" about "raising unrealistic expectations", Minister for Justice Michael McDowell, according to a spokesman, pointed to a series of unsuccessful excavations in recent years. "He is aware of the pain caused in the past when the families' hopes were raised then dashed by unsuccessful digs based on erroneous information," the spokesman said.
So far, officials believe that the IRA information was passed on in good faith, but some of the killers are dead, and most of the bodies were buried at night in remote areas, making tracking difficult.
Expressing his deepest sympathies to relatives, Mr McDowell said the Irish and British governments remained "committed to doing all that is reasonably possible" to find them.
The commission's members; former Secretary to the Government Frank Murray, who replaced former Tánaiste John Wilson, and Kenneth Bloomfield, ex-head of the Northern Ireland Civil Service, briefed relatives yesterday.
A forensic scientist will be retained on the staff, while an advertising campaign, special confidential telephone line and PO box will be created to encourage those with information to come forward.
DNA samples will be taken from the victims' closest relatives, surviving medical and dental records will also be gathered, while new forensic technologies will also be used.
The other "disappeared" are Séamus Wright, Kevin McKee, Columba McVeigh, Brendan McGraw and Danny McIlhone.
