Sinn Féin MLA Gerry Kelly said the latest report from the Police Ombudsman is a damning indictment of the RUC Special Branch.
And the Policing Board member said it highlights the need to implement the Haass proposals on dealing with the past.
Speaking following the publication of a Police Ombudsman's report which found that senior RUC officers could have prevented the killing of a police officer in 1977, Gerry Kelly said;
"This report confirms what republicans have said about the RUC Special Branch for many years.
“This force within a force showed complete disregard over decades for the lives and safety of the nationalist community.
“However, in the case of Joseph Campbell it was also clearly prepared to sacrifice the life of one of its own officers to protect an informer.
"This case details the rotten core of the RUC going back almost four decades.
"As the report clearly demonstrates, this cannot be explained away by pointing the finger of blame at individual RUC officers.
“The Head of Special Branch and probably even the Chief Constable knew of the threat to Sgt Campbell’s life and took no action to prevent his killing.
"Once again, like other investigations into collusion and wrongdoing by the RUC, former officers have refused to co-operate with the Ombudsman and key files have been destroyed.
"These continued attempts to block the truth, only adds to the pain and suffering of the victims.
“This case shows once again the need for mechanisms such as those contained within the Haass proposals to deal comprehensively with the issue of the past.” ENDS/CRÍOCH