More than 2,000 mobile phones have been seized by prison authorities this year, according to Prison Service figures.
Some 2,010 phones were found in 15 jails and institutions, with 687 phones found in Mountjoy Prison. Statistics for other years are not available.
So far, just 30 prosecutions have been launched over the discovery of the phones, which are illegal in prisons, according to figures released by Minister for Justice Brian Lenihan in response to a written question in the Dáil.
Criticising the figures, Fine Gael TD Lucinda Creighton said: "Far too little is being done to prevent criminal gangs from operating inside prisons."
The phones were being used by prisoners to continue their criminal activities.
Legislation introduced in May this year to ban phones in jails "was clearly not being enforced widely or strictly enough to deter hardened criminals from continuing to engage in organised crime", she said.