One of the founders of the SDLP has blamed DUP leader Ian Paisley for contributing to the "intensity" and "duration" of the Troubles.
Austin Currie, the only person to serve in parliaments on both sides of the border, said the 78-year-old unionist leader was more responsible than any other individual.
Mr Currie hit world headlines in 1968 when, as a member of the Stormont parliament, he squatted in a house in Caledon, Co Tyrone to highlight anti-Catholic housing policy.
His stand, and a subsequent civil rights campaign, is seen by many as the beginning of the Troubles.
Speaking in advance of the release of his autobiography this week, Mr Currie said he would not have taken a stand if he had known if would be followed by almost 4,000 deaths.
He said: "If I had known then what I know now, in view of the almost 4,000 people who lost their lives, would I have done what I did? No.
"But certain things that happened were not inevitable. It was not inevitable that the civil rights movement would be followed up by a campaign of violence. It was not inevitable that loyalism would respond in the way it did."
However, the person he blames more than any other for Northern Ireland's problems is the current elected leader of unionism.
"I have observed Ian Paisley for more than 40 years and I am of the belief that he has contributed more to the intensity and the duration of the Troubles, and therefore the deaths of so many people, than any other individual."
His view of the DUP's deputy leader is different, however.
During talks in 1988 at Duisburg in West Germany he came to a number of conclusions about Peter Robinson.
"I came to the conclusion that he would not be prepared to spend the rest of his political life on the back benches of Westminster, that he wanted to exercise power and he realised he could only exercise power in the context of a partnership arrangement with the representatives of the nationalist community. So I'm not surprised by the role which he is currently playing."
No DUP representative was available for comment last night (Sunday).
Mr Currie also said he believed that Sunningdale was in many ways a better deal for nationalist than the Good Friday Agreement.
"I think the council of Ireland, and particularly the second tier of the council of Ireland, which involved 30 members of the Dail and 30 members of the northern assembly meeting... was hugely symbolic of a development of a stage towards a united Ireland," he said.
