In a statement, PFNI chairman Mark Lindsay (pictured) said the incident underlined the need for a full inquiry into the operation of the police watchdog.

He said: “We are extremely concerned over this alleged theft of sensitive documents. There is a criminal investigation underway, but in a wider sense, I am concerned at the operation of the PONI.

“If PONI cannot be trusted with sensitive information, then there’s a good case to be made to restrict the data. There should be a full investigation by Information Commissioner into what appears to be a blatant breach of the Data Protection Act and the incident should also be reported to the Oversight Commissioner, who has responsibility for all information obtained under investigative techniques.

“In the recent past, we’ve called for a full inquiry into the operation of PONI. We now repeat that call. A full inquiry into the operation of the Police Ombudsman has now become a minimum requirement, in order that both the public and police officers alike can have confidence in the office. PONI appears to act without proper oversight or accountability and this must not continue.

“It’s time to look at the work that PONI undertakes; the way it conducts itself; the approach it takes into investigating Officers doing the best they can for the community, and the internal procedures that undermine confidence in the way it operates.”