An investigation into the Shankill Road bombing of 1993 which killed 10 people, including two children, has revealed that the person who planned the attack may have tipped off the MI5. There have been claims that security forces were informed about the bombing but failed to act to prevent it.
A fish store in Belfast was blown up by the Irish Republic Army (IRA) in a bid to assassinate the leaders of the Ulster Defence Association (UDA) including Johnny Adair, who were supposed to meet in a room above.
According to encrypted documents stolen by the IRA from the headquarters of the then Royal Ulster Constabulary (RUC) on St Patrick's Day, 2002, the informant was a British agent known as "AA" who sent the MI5 or RUC Special Branch a number of details regarding the plot, including the timing and the intended target.
The allegations against the MI5 first came to light in a report by the Irish News newspaper and were followed by a complaint to the Police Ombudsman for Northern Ireland by a relative of one of the victims demanding clarification of AA's relation to the RUC Special Branch or MI5.
In a statement on behalf of Dr Michael Maguire, the ombudsman, his office said: "We have received a complaint. It centres on two concerns: Did the RUC have information which would have allowed them to prevent the bombing and was the subsequent investigation compromised; (and) did the police 'fail to deliver justice to the families of those who lost their lives in the bombing'?
"We will seek to establish if this is something we should investigate, and if so, when we could begin this work."
Reports of the new allegations have led to more relatives of the victims coming forward seeking justice. Charlie Butler lost three members of his family and is now keen that a full investigation is held to look into the security bodies' involvement in the bombing.
BBC News reported him as saying: "Collusion is not a nice word for anyone but when it is collusion with innocent people losing their lives to protect someone else there has to be a line drawn to say that is wrong.
"(The security forces) were there to do a job, to protect people. If they knew about (the bombing) then they should pay."
The Shankill Road bombing missed its target as the UDA members decided to reschedule their meeting at the last minute and had already left the building by the time the bomb went off. Instead, the blast killed civilians, one UDA member and one of the two bombers, IRA man Thomas Begley, who had carried it into the store. Fellow bomber Sean Kelly managed to survive the blast but sustained injuries.
The incident is considered to be one of the most notorious acts of the troubles in Northern Ireland and led to a series of revenge attacks in which 14 people were killed.