Relatives of those killed in the Omagh bombing have said it is essential that they are represented by a special legal advocate in closed hearings at the public inquiry into the 1998 atrocity.
Much of the key evidence to be heard by the inquiry into the Omagh bombing is deemed secret and sensitive and will not be disclosed in open, public sessions.
That means survivors and relatives of the 29 people killed in the dissident republican bombing will not be allowed to hear it.
Relatives and survivors want a special advocate to be appointed to be their eyes and ears as they would have access to sensitive security evidence in secret hearings.
It would be their job to push for as much as possible of the closed material to be made public, and to ensure that the inquiry has access to all the material the families consider necessary.
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They would not be able to share the secret information with the relatives, but would be able to assure them that material had been provided and to raise their concerns with the inquiry team.
Two days of hearings about the issue are taking place in Belfast.
The inquiry was told yesterday that many of the relatives and survivors are "suspicious and even cynical" about the prospects of the UK state engaging with the inquiry in a straightforward and wholehearted manner.
Inquiry chair Alan Turnbull today raised concern about the possible negative perception the appointment of a special advocate might create, given that all of the core participants have expressed confidence in his team.
"It begins to sound a bit uncomfortable if you start with the premise that you have full confidence in the inquiry, independence of the inquiry, the independence and competency of the chair and the team, and yet, the core argument in favour of a Special Advocate is to ensure that they don't do something wrong," he said.
Michael Gallagher, whose 21-year-old son Aiden was one of those killed in the bombing, said the credibility and integrity of the inquiry team is not in question.
But he said the appointment of a special advocate is required.
"We have every confidence in Lord Turnbull and his senior legal team, absolutely," he said.
"But these are very complex issues that they're talking about and sometimes we have, it doesn't matter what country it is, the intelligence service, the government don't like their secrets known in public so a special advocate can actually pursue our interest if you like in closed session.
"We need answers to the questions that we've been asking for 27 years and a Special Advocate, in our opinion, is the best chance we have behind closed doors," Mr Gallagher added.
The inquiry, established to examine whether the bombing could have been prevented, will not begin those closed evidence hearings until early next year.
