Relatives of those killed in the Omagh bomb have said the government must demand an urgent meeting with the British to address claims that the bombers could have been stopped.

Michael Gallagher, whose son Aidan was killed in the blast, accused the government of "spinelessness" in not adopting a tough stance with Gordon Brown over allegations that British intelligence chose not to intercept the Omagh bomb.

"If the Irish government had any backbone, it would be raising the matter with the British," Gallagher said. "Three Irish citizens died in the bomb. Brian Cowen should be seeking an urgent meeting with the British prime minister and demanding answers.

"If China or Russia apparently failed to stop a bomb which killed British citizens, there would be an international crisis. The Irish government is shirking its responsibility."

Three Buncrana schoolboys – Oran Doherty (8), Sean McLaughlin (12), and James Barker (12) – were among the 29 people killed in the 1998 bomb. Last week, the BBC Panorama programme disclosed that British GCHQ (Government Communication Headquarters) was monitoring the bombers telephone calls.

There were nine exchanges between the bomb car and the scout car as they made their way from the Republic into Omagh. The first call monitored was as the bomb run began in Castleblaney, Co Monaghan.

Gallagher said: "GCHQ violating Irish airspace raises issues of national sovereignty. I expected Dublin to be demanding answers from Britain, asking why this happened, and requesting copies of the telephone transcripts. Yet the silence from Dublin has been deafening."

Political sources said "conversations about what the British intelligence services were up to are not ones the government wants to have". Following Panorama, the British government announced that intelligence services commissioner, Peter Gibson, would conduct a review into intercepted intelligence linked to Omagh. It will last three months.

Gallagher believed it should be completed far more speedily: "The archival material is probably sitting on a shelf and could be accessed and sent to us within days, if not hours."

Gallagher said the cross-border nature of the inquiry was vital as at least four agencies were involved: MI5; RUC Special Branch; Garda Crime and Security; and the FBI in the form of FBI/MI5 agent Dave Rupert, who infiltrated the Real IRA.

SDLP Assembly member, Alex Attwood, said his party had raised the need for the Government to support the demand for an independent public inquiry when it met foreign affairs minister Micheál Martin on Thursday. "The Irish government should be adopting a more robust approach to the issue than simply waiting the outcome of a secret British government review," Attwood said.

Gallagher expressed fears that the political and security establishment were trying to block the truth. "I can already see Gordon Brown reading a short statement to the House of Commons after this review. It will say, 'the government can now assure the House that nothing could have been done to prevent the Omagh bomb', and that will be it."

He said the British government was happier when the Omagh families were chasing terrorists, and seemed "more uneasy when we're holding the intelligence services to account".

Gallagher said "something dodgy" had happened in Omagh. "If it was just a cock-up, let them throw open the books and show us. But I suspect it's more than that – they have played a very dirty game."