The report was unlawful and procedurally unfair, Mr Justice McCloskey said, upholding the challenge brought by retired officers Ronald Hawthorne and Raymond White over the June 2016 report.

Mr Hawthorne brought the proceedings on his own behalf, while Mr White did so as chair of the NI Retired Police Officers Association.

Mr Justice McCloskey said the Police Ombudsman had not observed fundamental requirements “rooted in common law fairness”.

Those deemed to have colluded with loyalist gunmen “were, in effect, accused, tried and convicted without notice and in their absence”.

Handing down the judgment today, Mr Justice McCloskey added: “It is a matter of regret that as a result of this decision finality and closure for the affected families will be postponed once again.

“However, the task of the court is to conduct an independent and impartial adjudication and to dispassionately apply the relevant legal rules and principles to the material facts.

“This is the very essence of the rule of law. This exercise yields the outcome that this challenge succeeds.”

The issues of remedy and costs will be finalised at another hearing on Friday 12 January 2018, he said.

A spokesperson for the Police Ombudsman’s Office said: “We respect the judgment of the Court, and are clearly disappointed. We will need time over the coming weeks to consider it carefully.

“As we look at the judgment in more detail we will examine all the options open to us including an appeal. Clearly, however, we have to wait until the final outcome of the challenge.

“This judgment may have implications for how Northern Ireland deals with historical matters, affecting not only this Office, but also proposed solutions such as the Historical Inquiries Unit.”