Updated

Sinn Fein party leader Gerry Adams has rejected an ex-member's accusation that Adams authorized the 2006 Irish Republican Army killing of a high-profile informant.

The BBC's Spotlight investigative program in Belfast broadcast an interview with the man making the allegation on Tuesday night but shielded his identity, citing fears the IRA might try to kill him too.

The man, whom the BBC identified as a former member of the outlawed IRA and legal Sinn Fein who also informed for the British, said Adams approved the 2006 killing of former senior Sinn Fein official Denis Donaldson.

The BBC Spotlight documentary said senior IRA figures came under internal pressure to sanction Donaldson's killing by IRA commanders in South Armagh, a border region where suspected turncoats frequently were taken to be interrogated, tortured and slain. The man said Adams had "the final say."

Donaldson in December 2005 admitted he had secretly briefed police and British intelligence officers on IRA and Sinn Fein activities for two decades, an offense that typically merited the death penalty within IRA circles.

He moved from Belfast to live alone in an isolated farmhouse with no running water or electricity in the Republic of Ireland, where police found him shot to death five months later.

Nobody ever has been charged with Donaldson's killing. A splinter group nicknamed the Real IRA claimed responsibility three years later, but suspicions have persisted that Donaldson's former colleagues in the dominant IRA faction, the Provisionals, were responsible.

The interviewed informer attributed the killing to the Provisional IRA.

Adams said Wednesday he had no role in Donaldson's slaying and accused the BBC of reckless journalism, but stopped short of saying whether he would sue for libel.

"I very specifically and categorically and in a very unqualified way deny these allegations," Adams told Irish broadcasters RTE.