MI5 and MI6 have agreed to be central participants at an imminent inquiry into a paedophile ring at a notorious Belfast care home, the Court of Appeal heard.
Counsel for the probe into the Kincora scandal also insisted it has been given unrestricted access to information and documents from government departments and agencies.
The disclosure came during continuing legal action by one victim over claims of state collusion and the cover-up of sexual abuse throughout the 1970s in order to protect an intelligence-gathering operation.
Gary Hoy (54) is seeking to overturn a ruling that the examination should remain within the current remit of the Historical Institutional Abuse Inquiry (HIA) sitting in Banbridge.
His legal team claim that investigation, being chaired by Sir Anthony Hart, lacks the power to properly scrutinise what went on at the home in east Belfast.
They contend that the present arrangements cannot compel the security services to hand over documents or testify.
Instead, they are seeking a declaration that Mr Hoy is entitled to an inquiry that meets his entitlements to freedom from torture, inhuman and degrading treatment or punishment under Article 3 of the European Convention on Human Rights.
It is alleged the security service shielded and blackmailed those involved in child sex abuse at Kincora. Calls for scrutiny of the abuse have grown since three senior staff were jailed in 1981 for abusing boys in their care.
It has long been suspected that well-known figures within the British establishment, including high-ranking civil servants and senior military officers, were involved.
Last month the High Court dismissed Mr Hoy's legal challenge after finding it was premature. But with Sir Anthony's tribunal set to begin examining Kincora in just over a week, an urgent appeal against the verdict is under way.
Counsel for the HIA, Joseph Aiken, told judges attempts have been made through media commentary to undermine the inquiry's probe into the home.
He said unrestricted access has been given to all documents and information requested or considered relevant. "If those documents or parts of those documents are not made public then the chairman has made it abundantly clear he will raise the red card," Mr Aiken stressed.
The barrister went on to reveal who will have core participant status, allowing them legal representation at the hearings.
"The Kincora module will also have the PSNI, the Northern Ireland Office, the MoD (Ministry of Defence), the security service MI5, and the secret intelligence service MI6," he confirmed.
"The latter four are non-devolved departments and agencies, they have accepted the designation of core participants before this inquiry and are working to the inquiry's procedures."
The three appeal judges, led by Lord Chief Justice Sir Declan Morgan, were told there are no plans to have any closed hearings into Kincora.
And Sir Declan emphasised the gravity of the allegations surrounding events at the home. "If it's the case that children in Northern Ireland were abused in circumstances where public authorities were aware of it and used it for the purpose of gathering or securing information, that is so shocking that it needs to be exposed if it's true," he said.
Reserving judgment in the appeal, Sir Declan pledged to give a decision as soon as possible.