Gerry Adams "lied" by claiming he was never a member of the IRA, a former IRA member has alleged.
The ex-Sinn Féin president has consistently said throughout his life that he was never a member of the IRA.
However a BBC Northern Ireland Spotlight programme has aired a claim by Des Long - a former member of the IRA's ruling army council - that Mr Adams has lied about his membership.
The programme also quotes army intelligence from the time which said Mr Adams was understood to be leading the IRA in later years of the 1970s.
Mr Long claimed in an interview during the programme that Mr Adams was at one stage the chairman of the IRA's army council.
"You can't be on the army council unless you are a volunteer, and you can't be chairman of the army council unless you are a member of the army council," he told the programme.
"And I sat opposite him in meetings, this lie that he comes out with that he was never in the IRA. That's a lie.
"I say that now as having sat opposite him in meetings, probably get shot for it, but I'm saying it."
In May, Mr Adams told the Ballymurphy inquest: "I was not a member of the IRA, I have never disassociated myself with the IRA, and I never will, until the day I die."
Mr Adams declined to be interviewed for the Spotlight programme.
During the programme, journalist Darragh MacIntyre examines 1972, from being the year the IRA feted as their "year of victory", to what became the "long war".
It also examines the Ulster Workers' Council strike of 1974 and the collapse of the Sunningdale administration.
Last week, the first episode of the seven-part series marking the 50th anniversary of the start of the Troubles contained a claim that the Rev Ian Paisley funded a UVF bomb attack as well as airing footage of Martin McGuinness showing a gun to children.
Mr Paisley and Mr McGuinness went on to play key roles in the power-sharing Stormont Executive as first and deputy first ministers.
Both men have since died.
Mr Paisley's son Ian criticised the claim that his father funded a UVF bomb attack as "complete and total poppycock".