Home Secretary Theresa May has vowed the Security Service will co-operate fully with an investigation into a paedophile ring at the Kincora Boys' Home in east Belfast.
Ms May added she will be monitoring the case and will bring it into a powerful UK-wide inquiry with additional powers if necessary.
Scores of young boys were abused during their time at the children's home in the early 1970s.
There was disappointment last week when it was announced Kincora will not be included in a UK-wide Government investigation of historical child abuse.
In a letter to First Minister Peter Robinson, Ms May said she was "determined that everything possible is done to uncover the truth about what happened and that appropriate action is taken".
She added: "I want to take this opportunity to make it absolutely clear that all officials, Government departments and agencies will give their fullest possible co-operation to his inquiry.
"This includes the Security Service and Ministry of Defence, if it transpires they have any relevant information to share.
"But if this does not prove to be the case, then I will review the position and, if necessary, seek agreement to bring the Kincora allegations within the Terms of Reference of the Child Sexual Abuse Panel Inquiry, with the option of converting it into a statutory inquiry as necessary."