Sinn Féin said today that doubts cast by a former British MI5 officer on claims that Mr Martin McGuinness fired a shot before the Bloody Sunday massacre prove that the allegations were bogus.
The party was responding to a newspaper article by former intelligence officer Mr David Shayler claiming the agent behind the allegation at the Bloody Sunday Inquiry in Derry was a liar.
The inquiry, which resumes tomorrow, was told last April a document from an agent code-named "Infliction" revealed that Mr McGuinness, now the Stormont Education Minister appeared to have it on his conscience about firing a shot which sparked the massacre.
Thirteen civilians were shot dead by Paratroopers in Derry on January 30, 1972, while a Catholic civil rights march was banned. A 14th victim died later in hospital.
The families of those killed on Bloody Sunday and their supporters dispute that any shot was fired at the Army at all before the soldiers started shooting.
A debriefing note read at the Inquiry from Infliction claimed: "He (McGuinness) fired the first shot and nobody knows this.
"This seems to be on McGuinness's conscience. He has spoken to Infliction about it several times."
However, Mr Shayler said today that he intended to provide information to the Inquiry casting doubt on the agent's reliability.
He wrote in the Observer: "Infliction appeared to have particularly good access to IRA Northern Command.
"His information was taken seriously and acted upon for a while.
"Then, one day, there was a direct clash between Infliction's reporting and another source. Infliction was supposedly the reliable source and MI5 went with his version, only to be made to look stupid.
"As a result, it 'terminated' Infliction - ceased to use him as an agent - and labelled the intelligence he had provided as coming from a 'source whose reliability is being reassessed'."
Mr Shayler queried why evidence from Infliction was being used at the Inquiry chaired by Lord Saville.
He said the inquiry should be told if intelligence information it was given was questionable. He said he knew "many MI5 officers who could provide the information which I now hope to give to the Saville inquiry".
A Sinn Féin spokesman said Mr Shayler's remarks confirmed Mid Ulster MP Mr McGuinness's denial at the time the allegation was first made.
"When the allegation was first made, Martin said it had no basis whatsoever," the spokesman said.
"It proves what we have said all along that there is an attempt by the British intelligence services and the military to deflect from the actions of the Paratroopers on that day and from the proceedings at the Saville Inquiry.
"When Mr Shayler does give his evidence to the inquiry, this should be completely demolished."
PA