The Taoiseach, Mr Ahern, has said that the Garda Siochana and the RUC are closing in on the Omagh bombers. He warned, however, that those responsible for the "Real IRA" bomb attack last August, which claimed the lives of 29 people, could not be convicted on "hearsay".
He said the security forces could not be certain who carried out the attack. But he thought they were closing in on this group, he told Sky Television's Sunday with Adam Boulton programme.
"I think they have an awful lot of good intelligence. But they need more than that. They need to be able to prove it," Mr Ahern said.
"The security forces, like they never have before, are co-operating to try to find the perpetrators of Omagh."
He had seen speculation about the bombers' names, but warned that speculation was "a very dangerous business to get into."
He added: "I certainly believe that the security forces believe they are in the general area, and I hope that they are."
Meanwhile the Conservative Party leader, Mr William Hague, told the BBC's Breakfast with Frost programme that he asked the Tory MP Mr Andrew Hunter not to go ahead and name those he believed carried out the Omagh bombing, as well as "punishment" beatings and shootings.
"Naming and shaming" suspected paramilitaries would be a mistake in the present circumstances, said Mr Hague, who felt it could jeopardise investigations.
However, he insisted that it was also a mistake to go on releasing people convicted of terrorist offences.
"There is a danger that we will arrive at a point next year when we will have released all the terrorists, and they won't have handed in a single gun or bomb, and this sort of thing will still be going on. There will still be `punishment' beatings on a big scale in Northern Ireland," Mr Hague said.
