False identity cards and computer-altered passports and driving licences are being investigated by gardaí in Cork as part of a clampdown in the city on underage drinking.
Gardaí believe young people are using computers to make the fake ID cards.
Supt Kieran McGann said youngsters had been using the fake cards to get into certain pubs in Cork, where they were able to buy alcohol without difficulty.
Most publicans were extremely careful about the age groups they were serving, Supt McGann added.
But in a few cases, the false cards seemed to be accepted without much attention being paid by the publicans or their door staff.
Earlier this week, a city centre pub which served alcohol to a 17-year-old girl was ordered to close for four days by Cork District Court. The owners have 14 days in which to appeal.
It is understood that gardaí are also investigating computer-altered driving licences and passports which are also being used to gain entry to pubs and clubs.
The crackdown on underage drinking in the city was ongoing, Supt McGann said, and was being taken very seriously by gardaí in view of the latest statistics, which showed an increase in teenage intoxication in public places of 370 per cent since 1996.
He added that in 1998 there were 630 alcohol-related offences involving young people. The figure climbed to 760 in 1999, reaching 976 last year.
"This is obviously something we are taking very seriously. When the Garda-approved National Age Card Scheme is involved, there are few problems because it contains a hologram and is virtually foolproof."
The fake cards were causing problems but they wouldn't pass careful scrutiny, he said, adding that it should be possible to detect them with a little prudent examination.
"As well as investigating false identity documents we are actively involved in stamping out drunkenness in public houses.
"Gardaí are regularly visiting premises to establish if people who shouldn't be served are being served and, where necessary, we are taking the appropriate action," Supt McGann added.