The Irish Government has begun responding to "comprehensive" requests for information by a UK public inquiry investigating whether the 1998 Omagh bombing could have been prevented.
The news emerged during a procedural hearing in Belfast today.
In April, the Irish authorities signed a memorandum of understanding with the inquiry team covering how sensitive information held in Irish archives might be supplied to the inquiry.
The inquiry's terms of reference only cover whether the explosion, which killed 29 people and two unborn babies, could have been prevented by actions of UK state agencies.
But the bomb was built in the Republic, driven from there to Omagh and the bombers crossed back over the border after it was planted.
As a result the Omagh families have insisted the inquiry sees Irish intelligence archives and hears from Irish witnesses.
Requests have been submitted to the Government seeking information the authorities may have on events between 12-15 August 1998, covering the four days in the run up to the explosion.
This includes a "sequence of events" document requested of An Garda Síochána.
"The Government of Ireland presentation and an accompanying narrative explanation have now been received very recently from the Government of Ireland," inquiry counsel Paul Greaney KC told the hearing.
He said people could be reassured that the inquiry team would continue to meet regularly with Irish officials to "establish how their materials will be presented ... and how other government of Ireland officials are to give evidence in due course."
Mr Greaney said the Irish Government had other requests which it had still to respond to and had recently amended regulations under data protection legislation to support the Omagh Bombing Inquiry.
"We are grateful to the Government of Ireland for what it has done so far.
"But we have to add that there remains much work to be done."
Further public hearings in the Omagh Bombing Inquiry are scheduled to take place next March.
They will examine how the bombing was carried out and who may have been responsible.
In addition to the Irish Government, "very many requests" for information have been submitted to the UK authorities, including the PSNI, the British Ministry of Defence, the UK's Cabinet Office and Home Office, the National Crime Agency and others.
Mr Greaney said information had also been requested from both Essex Police and Greater Manchester Police about the capability of mobile phone cell site analysis in the mid nineties.
Those requests are linked to specific incidents including a gang-related triple murder in 1995 and the IRA bombing of the Arundel Shopping Centre in Manchester in 1996.
He said various archives and museums had also been asked for any relevant material and the inquiry team had sought information from prosecutors and courts in relation to relevant cases linked to the bombing.
A former British soldier who infiltrated the IRA along the border and supplied information to his handlers who uses the pseudonym Kevin Fulton, has also been contacted.
So too has former FBI agent David Rupert who informed his handlers on the activities of dissident republicans.
Evidence given in private at a Westminster committee in 2009 by former RUC officer Norman Baxter, the one time lead investigator into the Omagh bomb, has now been supplied to the inquiry following a petition to the UK parliament.
It is believed to be the first time such a petition process has been used to secure information by a public inquiry.
