A number of people linked by intelligence material to the murder of GAA official Sean Brown were British state agents, a court has heard.
A lawyer for the family of Mr Brown said the revelation was “shocking and upsetting”, adding that the case for a public inquiry to held into the death was now “overwhelming”.
The inquest hearing was also told that in excess of 25 people had been linked by intelligence to the murder.
Mr Brown (61) was abducted and killed by loyalists as he locked the gates at Bellaghy Wolfe Tones Club in Co Derry in May 1997.
No-one has been convicted of his murder.
His inquest began last year and is scheduled to resume in March.
Ahead of that, sensitive material relating to the murder must be security-vetted and distributed to the legal parties involved.
The public interest immunity (PII) process in the case has been taking place in closed hearings in recent weeks ahead of a ruling by coroner Mr Justice Kinney on Monday about what material can be considered by the inquest in open court.
Giving an update at the Royal Courts of Justice on Tuesday, counsel for the coroner Joseph Aiken KC, said he recognised that the PII process was “confusing and frustrating” for families.
He said a “global gist” had been arrived at to summarise what had been happening during the closed PII hearings.
He told the court: “Documentation produced to the coroner in the inquest by various agencies of the state consists of extensive relevant non-sensitive and sensitive material.
“The extensive relevant sensitive and non-sensitive material has been reviewed by the coroner in unredacted form.
“The material indicates that in excess of 25 individuals were linked through intelligence to the murder of Sean Brown.
“The intelligence material indicates that those individuals are said to have been involved at the material time with loyalist paramilitaries.
“Those individuals or potential suspects come from different geographical areas of Northern Ireland. Those individuals are not necessarily linked to one another.
“The intelligence material indicates that at the time of the death of Sean Brown, a number of the individuals linked through intelligence to the murder were agents of the state.”
Mr Aiken added: “Intelligence is not evidence but issues relating to the agents of the state and their handling would inevitably fall to be investigated in the inquest if it were possible for the coroner to do so.
“Agencies of the state, for longstanding reasons of national security in relation to source protection, have asserted public interest immunity in respect of material that substantially bears upon the issues which would otherwise be investigated by the coroner.”
Barrister for the Brown family, Des Fahy KC, then asked for a short break, noting the “audible and visible upset” from the family.
When the court resumed, he said the family had communicated their relief that Sean Brown’s widow Bridie had not been in court to hear the details given by Mr Aiken.
Mr Fahy added: “Material indicates in excess of 25 individuals were linked through intelligence to the murder of Sean Brown – the family note that not a single one of those individuals was charged with any offence in relation to the murder of Sean Brown, never mind brought to court.
“The upset and distress of the family is related directly to the content of that global gist.
“For many years they have made the case that there was collusion and the involvement of state agents in the murder of Sean Brown.
“Nevertheless, it is shocking and distressing to hear that in the context of this inquest.”
Mr Fahy said there was an “inevitability” that the inquest would not be able to consider issues relating to agents of the state on national security grounds.
“What I say on behalf of the families is that the case now for a full public inquiry into all the circumstances of the murder of Sean Brown is now overwhelming.”
The barrister added: “I ask the question on behalf of the next-of-kin. What is the attitude of the Secretary of State (Chris Heaton-Harris) to the holding of a public inquiry?”
He continued: “This is a very, very difficult day for the Brown family.
“Their focus now, if a viable inquest is no longer possible, is devoting all of their efforts to securing a full and meaningful public inquiry into the circumstances of this murder.”
