IRA members in Belfast remain unconvinced that Mr Freddie Scappaticci is not "Stakeknife" despite the Sinn Féin leadership's insistence that he must be treated as innocent until proven guilty.
At a press conference in Belfast last week, Mr Scappaticci denied he was "Stakeknife" and said he had never worked as a British army agent.
Mr Martin Ingram, a former British Force Research Unit handler, has called on "Stakeknife" to be taken into police custody so that the truth about British dirty tricks in the North could emerge.
Sources last night confirmed to The Irish Times that Mr Ingram had identified Mr Scappaticci as "Stakeknife" to the office of the Police Ombudsman, Mrs Nuala O'Loan, last August, when he met her investigation officers.
However, as the issues raised did not relate to police misconduct, the Ombudsman's office did not pursue the matter.
Instead, it handed over the details to the team led by Metropolitan Police Commissioner Sir John Stevens, who is investigating collusion between the paramilitaries and the security forces.
An IRA source in west Belfast, who would not be named, said no one wanted to believe allegations emanating from "the ranks of British intelligence". However, he said the "huge cloud of suspicion" over Mr Scappaticci had not been lifted and neither he, nor the Sinn Féin and Provisional IRA leadership, had explained many questions.
"Suspicions were aroused by the fact Scap didn't appear in public for four days after these allegations surfaced. Then, when he did appear it was very strange. We expected him to be flanked by a senior republican figure.
"That would have immediately ended speculation about his allegiances. But that didn't happen either. Sinn Féin is saying Scap is innocent until proven guilty. That is not the categorical denial of these allegations that you would expect in such a serious situation." He said it was significant there had been no such statement from the Provisional IRA leadership either which was "very tight" on information about "Stakeknife".
A middle-ranking IRA member in Ballymurphy said: "A lot of ordinary volunteers are very concerned by these allegations. They are frustrated because they don't seem to be getting answers.
"And some are getting angry because other people have ended up down a hole in the ground on very little evidence and yet the leadership has said it doesn't even want to question this man. We sense something isn't right." An IRA member from Ardoyne, north Belfast, said there are growing fears and resentment that Mr Scappaticci may have been "let off the hook" as part of a damage limitation exercise by the republican leadership.
"They know if they admitted he worked for the Brits for over two decades, their credibility would be seriously damaged. The IRA would be virtually destroyed. There is increasing suspicion that a deal has been done. He denies being an informer and gets staying in Ireland. They don't have to face huge embarrassment."
Another north Belfast IRA activist said: "I don't want to believe the IRA was penetrated at such a high level but I've heard nothing concrete from the leadership to reassure me. They should take action to set all our minds at rest."
Police special branch officers have carried out a raid on a London house used by a former intelligence agent who had threatened to reveal the identity of "Stakeknife".
The address used by Mr Kevin Fulton, a former soldier from south Armagh, who worked undercover in the IRA, was searched for several hours yesterday but officers left without making an arrest.