Northern Ireland’s chief constable has pledged “unfettered and unredacted access” to police files around the murder of GAA official Sean Brown for a public inquiry or a new body established by the Legacy Act.

Jon Boutcher was speaking days after the collapse of an inquest into the death of Mr Brown when a coroner ruled it was unable to proceed due to the withholding of sensitive files.

Mr Brown, 61, was abducted and killed by loyalist paramilitaries as he locked the gates at Bellaghy Wolfe Tones Club in Co Londonderry in May 1997.

No-one has ever been convicted of his murder.

On Monday, Mr Justice Kinney said his ability to examine the death had been “compromised” by the extent of confidential state material being excluded from the proceedings on national security grounds.

Announcing the Public Interest Immunity (PII) ruling in Belfast, the coroner said he will be writing to Northern Ireland Secretary Chris Heaton-Harris, calling on the Government to establish a public inquiry into the loyalist murder.

Mr Justice Kinney’s ruling comes after the Security Service, Ministry of Defence and Police Service of Northern Ireland (PSNI) applied for multiple redactions on sensitive files related to the murder.

Preliminary inquest proceedings have already heard that in excess of 25 people have been linked by intelligence to the murder, including several state agents.

It has also been alleged in court that surveillance of a suspect in the murder was temporarily stopped on the evening of the killing, only to resume again the following morning.

During a meeting of the Northern Ireland Policing Board on Thursday, Sinn Fein MLA Gerry Kelly asked the chief constable if he backed a public inquiry.

Mr Boutcher said he would, and also expressed regret that the Brown family had been “failed by the establishment”.

“Firstly I want to say with regards to the Brown family, this isn’t just words that often people portray, I am genuinely disappointed for them around the inquest,” he said.

“We know that inquests can work well for some families in legacy cases, but for other families because of the public interest immunity mechanism and the lack of a framework at inquest to deal with sensitive material, the inquest is not the route for the families to get the information.

“For me, and legacy is something that is very close to my heart, this is again us, the establishment, the institutions failing those families. My heart goes out to the Brown family, and I want to make very clear that Mr Brown was a man who had never done any wrong, he was an innocent member of the public going about his lawful business, a decent law abiding man who was murdered by terrorist thugs.”

All legacy inquests must be completed by May 1 or they will be transferred to the Independent Commission for Reconciliation and Information Recovery (ICRIR) set up by the Government’s controversial Legacy Act.

Mr Boutcher said he is looking at how to address the disclosure of sensitive information following May 1, and has discussed this with ICRIR chief commissioner Sir Declan Morgan.

“I’ve already had provisional discussions with Sir Declan Morgan around addressing this issue, where there will be unfettered access to that information, unredacted access to everything to Sir Declan Morgan. But I’m also looking at other ways that I can address what I think we can do more at with regards to that sensitive material in those cases,” he said.

“I do support a public inquiry. If there was any such inquiry set up, the PSNI would absolutely co operate with that inquiry and will provide that inquiry with all of the information, unfettered access to absolutely everything that we have collected with regards the Sean Brown case, that includes all of those files that were redacted. They will get those unredacted files.”