Gerry Adams, the Sinn Fein president, has denied sanctioning the murder of a British spy in the IRA.The allegation about the 2006 killing of Denis Donaldson was made by a man who claimed he was also a paid state agent in the IRA.The man made a series of claims, on an anonymous basis, to BBC Northern Ireland’s Spotlight programme.The most explosive was that Mr Adams sanctioned the killing of Mr Donaldson.Mr Donaldson, 55, a Sinn Fein official and close colleague of Mr Adams, was shot dead at an isolated cottage near Glenties in Co Donegal in April 2006.He had been living in the remote area of Donegal following his exposure as a state agent a year before his death.The Real IRA, a dissident republican group, claimed responsibility for the murder in 2008. A masked member of the Real IRA splinter group, which claimed responsibility for the murder of Denis Donaldson, reads a statement during a ceremony in Londonderry in 2011Credit:Peter Morrison/PA But the circumstances surrounding Mr Donaldson’s outing as a British agent and subsequent death have long been shrouded in mystery.The man interviewed by Spotlight said the IRA was responsible for the murder and that it was sanctioned by Mr Adams.The claim was rejected by the Sinn Fein leader, who has always denied he was in the IRA. Want the best of The Telegraph direct to your email and WhatsApp? Sign up to our free twice-daily Front Page newsletter and new audio briefings. Paramilitary groups killed or injured an estimated 3,000 people during the TroublesCredit:PA His lawyer told the programme his client had no knowledge of or involvement in Mr Donaldson’s death and denied being consulted over the killing.On Wednesday morning, Mr Adams wrote on Twitter: “Last night’s BBC Spotlights totally untrue allegations about me.” On the way 2 Ploughing.,doing LMFM’s Mike Reid Show @ 9.30 on last night’s BBC Spotlights totally untrue allegations about me.— Gerry Adams (@GerryAdamsSF) September 21, 2016 Mr Adams’s party colleague Gerry Kelly dismissed the documentary as a “collection of discredited conspiracy theories”.”The programme-makers have had no regard for the feelings of families of the victims of the conflict, including the family of Denis Donaldson,” said the North Belfast Assembly member.