The Taoiseach has described as "helpful" comments made by senior Sinn Féin figures urging anyone with information about the murder of Mr Robert McCartney to bring the information to his family.
Robert McCartney, who was fatally stabbed in Belfast
Sinn Féin TD Mr Caoimhghín Ó Caoláin asked the Taoiseach in the Dáil to note his "abhorrence of the brutal murder" of Mr McCartney following a brawl in a pub.
He said he wanted to repeat the call of his party leader Mr Gerry Adams for people to "assist the family in any way, and indeed in every way, they can in their quest for truth and justice in this case".
Mr Ó Caoláin also asked the Taoiseach whether it was now clear that there was no basis to the charge that the Sinn Féin leadership had prior knowledge of the Northern Bank robbery.
He said he appealed to the Taoiseach "calmly" for the need for clarity on this specific issue.
The Sinn Féin TD also asked Mr Ahern whether he had raised with the British Government the recent admission by MI5 that it had planted listening devices at a Sinn Féin office in Belfast.
He said Sinn Féin had been vindicated in its claims, which were dismissed at the time.
It had been a very damaging situation which the Taoiseach must insist never be repeated.
The Taoiseach acknowledged the TD's comments and Mr Adams's comments about Mr McCartney's killing and said this was "helpful".
Mr Ahern said he recalled the listening device in question being handed over by Sinn Féin at Leeds Castle last year and had made it clear at the time that the use of listening devices anywhere was not helpful.
He said the use of the devices hadn't been admitted at the time but added: "We certainly did on that day convey our abhorrence at the use of such tactics by MI5 or MI6."
Mr Ahern said he could not change his position on the Northern Bank robbery unless either the PSNI chief constable or the Garda Commissioner, who had given him the information, changed their position.
PSNI detectives frustrated by the silence surrounding the alleged IRA murder of Mr McCartney are hoping today's appeal by Mr Gerry Adams will help their investigation.
The Sinn Féin president last night urged anyone who knew anything about the stabbing of Robert McCartney during a Belfast pub brawl to alert the victim's family.
Sinn Fein's Mr Gerry Adams on the fatal stabbing of belfast man Robert McCartney
Even though no one has yet been charged with the attack on Mr McCartney (33), a forklift driver, the identities of his killers are widely known. His sister Paula, who blames an IRA gang for the killing, claimed republicans had frightened witnesses into silence.
The family received their first visit from a Sinn Féin representative yesterday when senior party member Mr Gerry Kelly went to their home in the Short Strand district of the city.
Later Mr Adams issued his call for any details to be passed on to the relevant authorities.
He said: "There are allegations that Robert McCartney was killed by republicans. I want to make it absolutely clear that no one involved acted as a republican or on behalf of republicans.
"I repudiate this brutal killing in the strongest terms possible." "No one has any right, as has been claimed, to prevent anyone from helping the McCartney family."
Ms Paula McCartney claimed the bar was forensically cleaned by IRA men who warned witnesses against talking about the attack. CCTV footage was also allegedly seized from the pub. She added: "It's a taboo subject, no one is allowed to speak about it.
"It's in the interest of the IRA to get rid of the murderers because they seem to be trying to destroy the organisation."
Additional reporting: PA