Claims of collusion between former officers and Northern Ireland terror groups have been challenged.

Frontline police leaders have criticised an official report which found evidence of collusion between officers and Northern Ireland’s loyalist terrorists.

The report into the Royal Ulster Constabulary by the Police Ombudsman raised “significant concerns” about conduct in relation to 19 murders and multiple attempted murders.

Ombudsman Marie Anderson reviewed 11 attacks carried out by the Ulster Defence Association (UDA) and the Ulster Freedom Fighters (the UFF was a cover name used by the UDA) between 1989 and 1993.

The 336-page report concluded concerns raised by bereaved families about collusive behaviours were legitimate and justified.

Her investigation included the RUC Special Branch’s use of informants who were themselves suspected of murder.

She found evidence of collusive behaviour among some officers but said the Royal Ulster Constabulary had no prior knowledge of the attacks.

An initial failure to tackle the threat posed by Loyalist groups was then compounded by subsequent errors.

“I am of the view that police were aware of the growing threat posed by the North West UDA/UFF from 1989 onwards,” said Mrs Anderson.

“This increased threat, however, was not initially accompanied by a policing response proportionate to the increased risk to members of the republican and nationalist communities.”

The ombudsman expressed concern that police had failed to deal appropriately with members of the security forces suspected of passing information to loyalists.

Officers had been dismissed or re-assigned rather than charged with offences.

 “I am of the view that the RUC response to these matters was both inconsistent and inadequate,” she said. ”I am of the view that allegations of RUC officers passing information of use to terrorists was a serious matter that should have been investigated robustly and consistently.”

The report also concluded that generally the investigations into the crimes were “prompt and thorough” by the RUC and a number of people responsible for the attacks had been brought to justice and convicted.

The issue of collusion runs right to the heart of The Troubles for Republican families, some of whom are now part of the political sphere.

So the leader of frontline officers in Northern Ireland said the choice of words in the final report should have been more careful and should have been backed with clear evidence.

Mark Lindsay, Chair, Police Federation for Northern Ireland (PFNI) said: “Once again we are disappointed that the phrase ‘collusive behaviour’ has been used by the Ombudsman without any evidence that could be tested in a criminal court.

“It goes without saying that with the benefit of hindsight that flaws in any investigation could be found, but such reports only serve to feed into uncontextualised attacks on policing at a time when there were unprecedented pressures because of relentless terrorist activity against all our communities,” he said.

The ombudsman’s findings seem unlikely to go further.

Two evidence files on other suspected criminality by two former police officers were sent to the Public Prosecution Service (PPS).

One was suspected of passing sensitive information to loyalist paramilitaries and the other of failing to disclose in a file to the then Director of Public Prosecutions that a suspect was also an informant.

The PPS has directed that neither of the former officers should be prosecuted.

But it still leaves the Police Service of Northern Ireland with a backlog of horrific cases that took place during The Troubles which remain unsolved with families on both sides of the sectarian divide still hoping for answers.

And the NI Federation said they had clearly suffered.

Mr Lindsey said: “This report deals with some of the most senseless and abhorrent terrorist attacks against innocent people and our thoughts are with the families of those who lost their lives as a result.”

He added the majority of RUC officers, who themselves had been terrorist targets, had done their duty and secured prosecutions as a result.

The Fed leader said: “What’s crucial here is that the police had no prior knowledge of the attacks reviewed by the Ombudsman. In addition, the report states that the Ombudsman’s office found no evidence that any officer had committed a criminal offence by protecting an informant from either arrest or prosecution and that, on its own, speaks volumes for the professionalism and impartiality of officers.

“Let’s not forget that only through thorough and dedicated police work that convictions were secured in the courts against terrorists who carried out these senseless and savage attacks.”