The Government has been accused of frustrating the release of files that expose a "state-sponsored programme of assassination".
A lawyer for the family of a father-of-three shot dead by loyalist paramilitaries made the claim during a Coroner's Court hearing ahead of a new inquest into the death.
Gerard Slane (27) was shot by the UDA at his home at Waterville Street, west Belfast, in 1988.
Barrister Fiona Doherty said the extent of collusion between paramilitaries and the security forces in the murder was "as bad as it gets" as she demanded an explanation for delays in disclosing police and military files.
"This was a state-sponsored assassination programme going on here of which Gerard Slane was an entirely innocent victim," she told coroner Suzanne Anderson at a preliminary hearing in Belfast Coroner's Court.
Ms Doherty was responding to the revelation that it will take at least six more months before files are handed over to the coroner.