Stanley McCombe believes that somebody, somewhere, decided they were expendable. The men, women, and children shopping in Omagh town centre that Saturday afternoon didn't count in the minds of those in the British intelligence services making life-and-death decisions.

"Had that bomb been heading for Hillsborough Castle (the Northern secretary of state's residence), or RUC or British Army headquarters, it would never have got through," McCombe says. "The security forces would have been told to seal off the place and arrest the bombers.

"But there were no VIPs on the streets of Omagh. It was only ordinary folk like my wife. They were worthless in the eyes of the state." McCombe, whose wife Ann was among the 29 people killed, is one of many relatives highly suspicious of the actions of the intelligence services in light of revelations on last week's BBC Panorama programme.

It was disclosed that GCHQ, the British government organisation for intercepting electronic communications, was monitoring the mobile phone calls between the bombers as they drove across the border on 15 August 1998.

It hasn't yet been proved whether these calls were being listened to live or just recorded. Most relatives suspect the former, a belief shared by a well-placed political source who spoke to the Sunday Tribune. With an annual budget of £800m and a 4,000 strong staff, GCHQ wasn't short of resources.

The priority the intelligence services gave to the Real IRA is evidenced by the millions of pounds spent in having FBI/MI5 agent, Dave Rupert, infiltrate the organisation and befriend Mickey McKevitt.

Conspiracy theory

The fact that information from the Omagh phone bugging wasn't used to effect, even in the vital hours and days after the bomb, gives more weight to the conspiracy theory. The bombers' homes weren't raided and the complete phone intercepts were never passed onto lower-ranking detectives investigating the attack.

Michael Gallagher's son Aiden, 21, was among those killed. He believes one of the reasons for the non-action was that several of those involved in the attack were intelligence service agents. It is widely believed the bomb-maker, a Newry man living in Dundalk, was an agent.

Similarities have been made to the murder of Belfast solicitor Pat Finucane – several members of the UDA killer gang were agents.

The Sunday Tribune has also been told that an American spy satellite was monitoring the bombers' conversations.

Gallagher fears that the lack of action over Omagh wasn't simply a cock-up. "Omagh was a very convenient atrocity," he says.

"It was used to strengthen the Good Friday Agreement. The government could point to the carnage in Omagh and say to the politicians and the public: 'it's the peace process or more of this'." Had a bomb killed civilians in a mainly Protestant town – previous dissident targets had been Portadown and Banbridge – it would have shattered the peace process.

Spirit of reconciliation

But Omagh, religiously mixed with a nationalist majority, was a place where the spirit of reconciliation was always going to predominate. From the intelligence services' perspective, Omagh could have been seen as the bomb to end all bombs. "They might have thought it a way of demolishing the Real IRA," Gallagher says.

Formed nine months earlier, the Real IRA had been waging a high profile campaign – including attempts to bomb Britain – and securing recruits from Provisional IRA ranks. The wave of public revulsion after Omagh halted this and forced the organisation to call a ceasefire.

Gallagher says an independent, cross-border public inquiry is the only way forward: "I believe someone in the intelligence services took a decision not to intercept the Omagh bomb, that they decided to play Russian roulette with our loved ones' lives.

"I want to know who that person is and whether they are still in a position of power. I want to know how many other vital decisions they've taken in the 10 years since. I want to know who decided not to act on all the information afterwards. These faceless people in the intelligence services would have watched the scenes of carnage in Omagh on their televisions.

"They would have seen our heartbreak. They would have heard us plead for information to catch the bombers. They would have tucked their children into bed while we buried ours. At the very least, they owe us an explanation." Gallagher stresses he is not anti-security force. His brother was a former UDR member. His suspicion and anger is targeted at "the top police and military brass".

Sacrificed by the state

Lorraine Wilson, 15, was working in the Oxfam shop in Omagh when she died in the bomb. Her father Godfrey says: "The nightmare scenario in my head is that agents of the state were involved in the bombing, that there's a Mark Haddock (UVF police informer named in the Dáil as being responsible for many murders) involved.

"It horrifies me to think that my daughter, out doing charity work, might have been sacrificed by the state. What's the point in having agents, if you don't act on their information to save lives?

"When Lorraine finished primary school, she put her wee books, pencils, and sharpener in a shoe box in the attic. Even now, we can't bear to open it."

'To hell and back'

Stanley McCombe, whose wife Ann was killed, is angry that the information about the bombers' phone conversations had to be "prised out" by a journalist. He thinks the upper echelons of the security and political establishment are "a shower of you know whats".

"After Omagh, so many powerful people promised so much," he says. "I met Bill Clinton, Tony Blair, and Bertie Ahern in Omagh leisure centre. Blair had that oul' false smile on his face. They all offered their condolences and said no stone would be left unturned in our search for justice. What a pack of lies that was.

"It doesn't matter what agenda the establishment had in terms of withholding information about the bomb. They sent us to hell and back. I don't give a toss about the so-called interests of Northern Ireland or Britain or Ireland. I just want my wife back."