The former boss of disgraced spy Mr David Shayler today said intelligence provided by an IRA informer known as "Infliction" was regarded by her colleagues as being of "mixed reliability".
"Infliction" has claimed Sinn Fein's Mr Martin McGuinness told him he fired the first shot on Bloody Sunday.
But Mr Shayler earlier claimed he was told by at least two MI5 officers that Infliction was regarded as a "bullshitter".
His group manager in the section dealing with the threat on the British mainland from Irish terrorism during the 1990s, Officer E, today told the Saville Inquiry in London she was aware of the existence of Infliction for a number of years.
"Although I don't recall when I first heard this, I do have a general recollection that his reporting was considered by others to be of mixed reliability," she said.
"As far as I recall, I gained this impression from hearing others comment on Infliction and/or his reporting and not from any written documents."
However, the serving MI5 officer said she was not an appropriate person to comment on Infliction's reliability as she was not his handler.
Mr McGuinness, who has admitted to being the IRA's second-in-command in Derry in January 1972, has denied the informer's allegation.
Mr Shayler appeared at Methodist Central Hall in London yesterday followed his early release from a six-month prison sentence after he was convicted of breaking the Official Secrets Act by disclosing information to a national newspaper.
PA