A British attorney general shouted "we must kill Paisley" after waking up from surgery, according to newly declassified state papers from Dublin.
Sir Michael Havers said his wife and surgeons were at his bedside as he yelled out the remark having regained consciousness after a heart operation.
Sir Michael, father of the actor Nigel Havers, was attorney general from 1979 to 1987,
He said he could not explain the remark about the then DUP leader.
Sir Michael recounted the incident at a January 1987 meeting with Irish diplomat Richard Ryan, who recorded it in a written note sent back to Dublin.
Also present at the meeting was Conservative MP Ian Gow, who had resigned from Margaret Thatcher's government in protest at the Anglo-Irish Agreement of 1985, which gave Dublin a greater say in the affairs of Northern Ireland.
According to the record of the meeting, Mr Gow was "very depressed" prior to Sir Michael's arrival, describing unionist leaders who opposed the Anglo-Irish Agreement as "hopeless and awful".
The note said he was "very angry" at the UUP leader Jim Molyneaux, who "chickened out" and did not go to a secret meeting with the then Taoiseach (Irish Prime Minister) Garret Fitzgerald.
In a separate memo, Dr Fitzgerald noted that he had hoped to meet a senior unnamed unionist politician but that it did not come to fruition.
While Mr Gow temporarily absented himself, Sir Michael and the Irish diplomat discussed lobbying to get Mr Gow back into government.
When he returned to the company, Mr Gow, in turn, urged Sir Michael to lobby for Sir Patrick Mayhew to replace him as attorney general.
Sir Patrick did succeed Sir Michael as Attorney General later in 1987.
But Ian Gow never returned to government.
He was murdered by the IRA in a car bomb outside his home three years later, in 1990.