Six retired RUC officers are considering legal action against the Police Ombudsman after their personal details were leaked.
A former ombudsman's investigator was arrested this month as part of an investigation into the alleged theft and disclosure of sensitive documents.
It is understood at least eight former police officers were named in papers unlawfully disclosed to a law firm.
Six of the officers have now asked a lawyer to prepare legal action.
The lawyer has written to the Police Ombudsman, Dr Michael Maguire, asking for a detailed explanation of what sensitive information was unlawfully disclosed.
He has also written to Chief Constable George Hamilton asking for an outline of action taken by the police to recover the documents, and any copies that may have been made.
It is understood the police and the security service MI5 believe the information disclosed could potentially put the lives of individuals at risk.
A 69-year-old man was arrested in Dartford, Kent, earlier this month.
It is understood he retired from the ombudsman's office a number of years ago.
However, the lawyer acting for three former Special Branch officers and three detectives has said the documents at the centre of the investigation are connected to an incident currently being investigated by the ombudsman.
The Police Federation of Northern Ireland has called for a "full inquiry", and described the alleged theft and unlawful disclosure as an "astounding and very worrying state of affairs".
The police have suspended the release of any further sensitive material to the ombudsman's office until a review of security protocols is carried out.