The association representing off-licence owners has blamed under-age drinking on the "despicable practice" of adults buying alcohol for minors.
A spokesman also predicted that the deregulation of licensing under a new Government Bill will "multiply" the opportunities for young people to buy drink.
Mr John Shiel, chairman of the National Off-Licence Association, was responding to suggestions from two TDs - Fianna Fáil's Mr Batt O'Keeffe and Labour's Mr Joe Costello - that the introduction of identifying labels on drink packaging would stamp out the problem.
Such a move would be happening anyway under EU legislation to be enacted next January, Mr Shiel said.
But his association had already pointed out to Government that the inclusion of traceability codes on packages would be undermined by the "grossly irresponsible action" of adults buying drink for youngsters.
"For members of the Oireachtas to suggest that the labelling of every alcohol container will of itself stamp out underage drinking, is grossly over-simplistic and disingenuous," he said.
He predicted that the burden of proving underage sales could become a "nightmare" for gardaí.
"The Dáil members concerned do not seem to be aware of the impending EU legislation, and instead of pressing for its introduction, which is already in train, they would be better occupied by seeking to have the law-enforcement capabilities of An Garda Síochána enhanced."
Mr Costello, Labour's justice spokesman, had complained about the level of drinking in parks and other public places, and said most of such alcohol originated in off-licences. But criticising the Minister for Justice for failing to produce a "proper national ID card", Mr Shiel suggested that TDs should focus their energies in this direction.
"They should also, as a matter of extreme urgency, focus on the implications of the proposed new regulations governing licensing in Ireland, the heads of Bill for which were put before the Cabinet before the summer recess.
"If the new regulations become law, the sale of alcohol will be deregulated to such an extent that the opportunities for young people to access alcohol will be multiplied.
"Retail outlets from chippers, to video rental shops, sweet shops, late night take-aways, even cinemas will for the first time be in a position to sell alcohol under the proposed new licensing laws."
