The Office of the Surveillance Commissioners (OSC) praised the PSNI for standards "practically unheard of in any organisation".

The OSC's most recent report was issued weeks before its chief meets the Policing Board chairman to discuss UVF informer Mark Haddock.

Police Ombudsman Nuala O'Loan raised questions over the OSC's monitoring in her devastating report on Haddock's activities - including his links to 10 murders - produced this year.

The OSC has not responded publicly to her comments or a recommendation that they consider whether their inspection processes are "adequate".

Policing Board chairman Sir Desmond Rea is due to hold a follow-up meeting with the Chief Commissioner, Sir Christopher Rose, later this year.

Prior to Mrs O'Loan's investigation, inspections by the OSC made some criticisms of the PSNI but failed to uncover the breaches relating to Haddock.

The OSC also missed the involvement in serious crime by (according to the PSNI's own calculations) more than 10% of its informers.

The police dropped those informers and an equal number were deemed inactive after an internal review in late 2003.

According to Mrs O'Loan, the OSC reported in February 2003 that there were some failings by the PSNI, but declared the majority of Special Branch informers "well-handled and controlled".

Seven months later Mrs O'Loan's investigators alerted the OSC about Haddock's activities, which included involvement in drug dealing and other paramilitary crime while under police pay. The OSC carried out another inspection in October 2003 on the basis of the Police Ombudsman's information and concluded Special Branch "failed to meet national minimum standards".

They also declared Haddock to be a "high-risk source".

The Ombudsman's report suggests that the OSC may have been unable to find out about Haddock because police filed reports about him that were " selective, biased, and misleading" and in some cases "manifestly untrue".

In the OSC's most recent report, Sir Christopher concluded that the PSNI " had six examples of best practice, which is practically unheard of in any organisation. Our overall impression is that this is a Service working hard to overcome ... criticism of past activities."

The PSNI described the OSC's reports as "amongst the most searching" . While PSNI Chief Constable Sir Hugh Orde described the latest report as a " ringing endorsement".