A garda colleague of Sergeant Maurice McCabe has alleged the whistleblower sexually abused his young daughter.

The Disclosures Tribunal has been hearing evidence from the social worker involved in the case.

This morning they drilled down into the initial allegation of sexual abuse made against Sergeant McCabe.

The allegation came from Miss D - a teenager who was involved in social care services since 2005.

In 2006, Miss D made a claim of sexual abuse following an incident which allegedly occured in 1998 when she was 6 or 7-years-old.

The retrospective allegation was that during a game a man held her over a sofa; they were fully clothed but there was humping involved.

Miss D's father - who was a guard and a colleague of Sgt Maurice McCabe - alleged that Mr McCabe was the man involved.

After looking into it, the DPP decided not to prosecute - and social workers decided the case was inconclusive and closed it in 2007.

They said there were no complaints from any other parties against Mr McCabe.

The wider allegation for this tribunal is that the files from this case re-surfaced and that false allegations were made by senior members of the gardaí in a smear campaign against Sergeant McCabe.

The first day of evidence is continuing at Dublin Castle this afternoon.