The former politician was killed in 2006 after being exposed as a British spy
Gerry Adams has said allegations he was involved in the murder of IRA informer Denis Donaldson are "a lie".
A BBC 'Spotlight' programme last night suggested that Deputy Adams gave the go-ahead to kill Mr Donaldson in 2006, because Republican Thomas 'Slab' Murphy wanted him dead.
The claims were made by a man known only as 'Martin', who says he worked for the RUC as a mole inside the IRA since 1997.
The Sinn Féin leader has denied all involvement and said the matter is with his solicitor.
"I categorically and specifically deny it," he said. "We have to look at what's behind this agenda [...] This is an attempt to rewrite history."
Sinn Féin MLA Gerry Kelly has also criticised the broadcast and its contents.
Mr Kelly said the programme was "a collection of discredited conspiracy theories which relied on the claims of an anonymous paid liar and British agent".
"The programme makers have had no regard for the feelings of families of the victims of the conflict, including the family of Denis Donaldson," he added.
Mr Donaldson was shot dead in the Doochary area of Donegal in April 2006.
It happened months after the former Sinn Féin politician and official was exposed as an agent who had worked for MI5 for over 20 years.
The party's TD Martin Kenny has also rubbished the claims about the murder.
"Every so often we have all these claims coming out about different things that happened during the conflict or in the aftermath of the conflict," he argued. "Ireland has moved on, and it's a good job it has, and we're all hoping to move on with it."