The Taoiseach, Mr Ahern, last night reiterated the Government's position that "no effort" would be spared to bring to justice all those responsible for the Omagh bombing.
He was commenting after the conviction yesterday of Dundalk man Colm Murphy on a charge of conspiracy to cause the bombing, in which 29 people died.
It was described yesterday as the biggest single atrocity of the Troubles.
Murphy, who was on bail but is now in custody, will be sentenced on Friday morning. The charge carries a maximum sentence of life imprisonment.
The three judges of the Special Criminal Court found that Murphy lent his mobile telephone, and that of an employee, to a man from Cullaville, on the Louth border, who was Snamed in court as Seamus Daly.
The telephones were traced as they were used by the bombers on the journey from south Armagh to Omagh and back.
A call from Murphy's mobile was made in Omagh an hour before the bomb exploded, just after the Vauxhall Cavalier used in the bombing was parked in Main Street.
It exploded at 3.10 p.m., causing what both the Taoiseach and Judge Barr described yesterday as the worst atrocity of the Troubles.
Murphy's mobile phone was also used by the "Real IRA" bombers during the bombing of the centre of Banbridge, Co Down, two weeks before the Omagh bombing.More than 30 people were injured in that attack.
In their judgment yesterday, the three Special Court judges referred again to "wrongdoing" on the part of two detectives involved in the interrogation of Murphy at Monaghan Garda station in February 1999.
Judge Barr said they had falsified part of a statement relating to a woman who had been one of Murphy's alibi witnesses.
However, the judges found that other detectives faithfully recorded Murphy's admissions about handing over the telephones.
The Garda Commissioner, Mr Pat Byrne, has appointed a senior Dublin detective to investigate the allegations that part of Murphy's alleged statement was rewritten in Monaghan Garda station.
In yesterday's judgment reference was made to Murphy's previous criminal record: that he had been imprisoned in both the United States and in the Republic for arms offences relating to Provisional IRA activities.
Murphy is the only person to have faced a charge in relation to the Omagh atrocity in which 29 people, including a woman pregnant with twins, died.
Yesterday relatives of the Omagh bomb victims urged the British and Irish governments to bring the Omagh bombers to justice.
Some of the relatives have started a High Court action seeking compensation against five men who they claimed were involved in the atrocity.
Assistant Garda Commissioner Kevin Carty, who headed the investigation in the Republic, said the Garda investigation was still "very much active and alive".
He said that the conduct of officers who were criticised in court would be addressed.
Murphy (49) owns the Emerald Pub in Dundalk and has a sizeable building contracting firm.
The Labour Party justice spokesman, Mr Brendan Howlin, said the criticisms of a number of gardaí made during the trial "are among the most serious to have ever been levelled by a judge against members of the force".
He pointed to "the court's description of the conduct of certain officers as outrageous and the designation of them as discredited witnesses who, in one case, was guilty of 'patent falsification'."
But he acknowledged that it was the testimony of another garda that exposed the falsification.