The report was presented to members of the Policing Board last week – six months after it was first requested.

It has been criticised by board members, however, as being “vague” and will not be released to the public.

It confirms that there are fewer than 10 incidents relating to lawyers and also to journalists. The report was requested after it was revealed that two journalists, Barry McCaffrey and Trevor Birney, had been put under surveillance.

Their case is under consideration at the Investigatory Powers Tribunal (IPT) in London.

Amnesty international and the Committee on the Administration of Justice have expressed concern about the surveillance operations being conducted against journalists.

Patrick Corrigan, Amnesty International’s director in the north, said a “free press and an independent legal system are cornerstones of any democracy”.

“It’s chilling that the police have apparently been conducting covert and intrusive surveillance on lawyers as well as journalists in Northern Ireland,” he said.

“We already knew about three incidents of police surveillance of journalists, but this new information seems to confirm our fears that these incidents are part of a wider pattern of the police abusing their powers on secret surveillance.

“We continue to call on the Policing Board to hold an inquiry into potentially unlawful use of covert surveillance. It’s time for full transparency, scrutiny and accountability.”

Daniel Holder, CAJ director, said: “Police spying on lawyers and journalists is often associated with undemocratic regimes – it requires compelling justification.”

He added: “The proper functioning of the legal system is reliant on confidentiality of legal communications between lawyers and clients.”