Sinn Fein's former leader, Gerry Adams

Veteran Limerick republican Des Long, who spent 17 years on the IRA’s executive, makes the allegation in a major BBC Spotlight programme to be broadcast tonight.

The film, part of a seven-part BBC series which has taken two years to make, also contains a series of other sources which place Mr Adams as a senior IRA figure in the 1970s.

The former West Belfast MP, who is now a TD for Louth, has always vehemently denied that he was ever a member of the IRA.

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Sinn Fein's former leader, Gerry Adams

Mary Lou McDonald, who succeeded Mr Adams as Sinn Fein leader more than a year ago, last year told the News Letter that she believed Mr Adams’ denials of ever having been a member of the terrorist organisation.

Tonight’s programme features an interview with Mr Long. Prior to falling out with Mr Adams during the republican split of 1986 and being involved in setting up Republican Sinn Fein, Mr Long told BBC Spotlight reporter Darragh MacIntyre that he had worked closely with Mr Adams.

He said: “The chairman of the army council would turn up to the executive meetings – we were meeting at least every four months.”

When asked who the chairman of the IRA army council was, Mr Long said with exasperation: “Gerry Adams.”

When it was put to him that Mr Adams says he was never in the IRA, Mr Long laughed and said: “You can’t be on the army council unless you’re a volunteer. And you can’t be chairman of the army council unless you’re a member of the army council — and I sat opposite him...and I’m saying that now, having sat opposite him in the meetings. Probably get shot for it. But I’m saying it.”

Spotlight said that Mr Adams had declined to take part in the programme.

The News Letter last night put Mr Long’s comments to Mr Adams via Sinn Fein but there was no response.

However, in the past he has denied ever being in the IRA.

The programme also includes an interview with retired British general Lord Ramsbotham.

He said that the Army believed that Mr Adams had “never used a pistol or thrown a bomb, but he was definitely a strategic planner of the highest order” within the IRA.

He said that he was told that Gerry Adams was “chief of staff or whatever” of the IRA.

Spotlight said that it had obtained secret Army reports which indicated that the military had no doubts that Mr Adams was a senior figure in the IRA.

The programme contains an interview with another former IRA man who questioned the purpose of what he and his colleagues had done.

Former IRA member Tommy Gorman broke down after saying of the IRA’s long campaign of violence: “What the f**k was it all about?”