Sinn Féin president Gerry Adams has denied any involvement in the abduction and murder of mother-of-10 Jean McConville in 1972.
The allegation is contained in a new book, Voices From The Grave, by former Irish Times Northern Editor Ed Moloney.
The book contains testimony from Brendan Hughes, a former IRA commander and close colleague of Mr Adams who died in 2008.
Jean McKendry, a daughter of Jean McConville said today she would begin a civil action against Mr Adams in connection with her mother's disappearance and death.
Mr Hughes, in a series of interviews given to historians at Boston College in the US n 2001 and 2002 on condition that they not be published until after his death, claimed Mr Adams was implicated in Mrs McConville's murder.
"I find it difficult to come to terms [with] the fact that this man [Gerry Adams] has turned his back on everything that we ever did," he is quoted as saying. "I never carried out a major [IRA] operation without the okay or the order from Gerry."
However Mr Adams today denied involvement in the death of Mrs McConville, who was accused by the IRA of being an informer, or of being a senior IRA figure. He accused Mr Moloney and colleague Anthony McIntyre of being biased against him.
"I knew Brendan Hughes well. Better than Ed Moloney or Anthony McIntyre," he said. "He wasn't well and hadn't been for a very long time, including during the time he did these interviews. Brendan also opposed the IRA cessations and the peace process. That was his right."
"I reject absolutely any accusation that I had any hand or part in the killing and disappearing of Jean McConville or in any of the other allegations that are being promoted by Ed Moloney."
Mrs McKendry said of her intention to pursue a civil case against the West Belfast MP: "Gerry Adams has to come out and tell people the truth. It is not just my family. It is everybody that was disappeared, that was hurt, killed or whatever during the whole Troubles in Northern Ireland. He needs to tell the truth."