Relatives of some of the ten Protestant workmen killed by the IRA in Co Armagh in 1976 have accused the authorities in Dublin of not cooperating with the inquest into the deaths.
Speaking outside Belfast Coroners' Court, DUP leader Arlene Foster said the issue had been raised with both Enda Kenny and Minister for Foreign Affairs Charlie Flanagan and she will bring it to the attention of the next taoiseach.
The ten men were travelling home from work in a textile factory when their mini-bus was ambushed.
After checking their religion, the gang ordered the one Catholic worker on the bus to leave before opening fire.
An 11th man, Alan Black, who was shot several times, survived the attack.
It has been claimed that the gang involved availed of the border to help carry out the attack.
Last year it emerged that a palm print of a Co Armagh man had been found in a van that may have been used as a getaway vehicle.
The vehicle had been stolen near Dundalk in Co Louth on the afternoon of the murders.
It was subsequently located by gardaí in a different part of Co Louth after the attack.
The PSNI reopened an investigation following the discovery of the palm print and a man was arrested.
However, Northern Ireland’s Public Prosecution Service confirmed in February that he would not face prosecution as there "is no reasonable prospect of a conviction, based on the available evidence".
During the inquest, which got under way this morning, a barrister representing some of the families has claimed a key suspect was linked to 46 murders between 1974 and 1976.
He said the detail is in a PSNI review of the case.
The inquest is expected to continue for another two weeks.
