Relatives of those killed in the Omagh bomb have said the government must demand a meeting with Downing Street to address claims the bombers could have been stopped.

Michael Gallagher, whose son Aidan was killed in the blast, accused the government of "spinelessness" 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. Last week, the BBC's Panorama disclosed that British intelligence was monitoring the bombers' phonecalls.

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

Gallagher said "something dodgy" happened in Omagh. "If it was just a cock-up, let them throw open the books and show us."