Taoiseach Enda Kenny has vowed that Garda files on the Kingsmill massacre will be handed over to the Northern Ireland coroner as early as next week.
Days after families of the victims denounced the delay as bordering on disgraceful, Mr Kenny said there were "genuine" legal issues holding up the disclosure of the official records.
Pressed about the issue at the North South Ministerial Council in Dublin, the Taoiseach said difficulties arose because Northern Ireland's coroners service was not a State body.
For the Republic of Ireland to issue the files, it was necessary to get a "government decision in principle" and then a "directive by the Minister for Justice" to grant the request, he said.
"I do hope we can conclude it on Tuesday and I will be speaking with the Attorney General later," he said.
"The reason for the delay was a number of genuine legal queries that came after we made the decision to supply the information."
Justice Minister Frances Fitzgerald brought a memo to the Dublin coalition Cabinet on Tuesday asking for agreement on handing over the files.
This was approved, according to Mr Kenny, and Ms Fitzgerald is now expected to order the Garda to give the coroner the relevant documents.
The Taoiseach said he has spoken on the telephone with Alan Black, the sole survivor of the massacre, and he was "very grateful " for the co-operation.
Earlier this week, lawyers for those bereaved by the murders in Co Armagh in 1976 heavily criticised officials in Dublin for not passing over the Garda documents, more than two months after Mr Kenny publicly committed to the handover.
The coroner's court was told the state solicitor's office in the Republic had written to say it was not in a position to give a date for disclosure.
The murders, which were widely blamed on the IRA though the organisation never admitted responsibility, involved a cross-border element, with the vehicle used by the killers stolen and then dumped in Co Louth.