State papers containing details of meetings between the Irish and British prime ministers around the time of the Anglo-Irish Agreement are to be made public in January.
The signing of the deal between Garret Fitzgerald and Margaret Thatcher in November 1985 – giving a greater say to the Republic of Ireland in affairs north of the border – sparked widespread unionist anger, leading to strikes, rallies and civil obedience.
There were also violent clashes between police and loyalist protestors.
Announcing the release of the files from early January, Irish heritage minister Heather Humphreys described 1985 as “a fascinating period in Irish history”.
She said: “Our archives are an invaluable resource. They are a witness to past events and I expect that the 1985 papers will shed new light on the challenges faced by state authorities at the time.”