Almost 1,300 drug seizures were made in prisons last year, it has emerged.
Fine Gael said the latest figures highlight the need for known drug addicts to have no-contact screened visits.
The party's justice spokesman Charlie Flanagan maintained the extent of drug abuse within the system also makes a mockery of commitments by the Government to abolish the scourge of addiction in prisons.
"As far back as 2004, the then Minister for Justice committed to ridding Irish prisons of drugs," said Mr Flanagan. "Six years later and the evidence is that our prisons are still rife with the scourge of drug addiction.
"A prison is supposed to be a secure institution. If prisoners can access drugs, it is no wonder they have little difficulty smuggling in mobile phones - 2,174 of which were confiscated last year. If the minister can't secure our prisons how can we expect him to secure our streets?"
Fine Gael said Justice Minister Dermot Ahern revealed there were 1,293 drug seizures in prisons in 2008, including 547 in Mountjoy alone.
Some 167 were made in Wheatfield, 97 in Cloverhill and 93 in the Midlands. Another 92 seizures came from young offenders in St Patrick's Institution.
Mr Flanagan dismissed assertions that seizures are proof that detection is effective.
"It proves only that a chronic drug problem exists and that mobile phones are still commonplace behind our prison walls," he continued. "The minister must consider the introduction of no-contact screened visits for known addicts.
"Otherwise a prisoner who enters prison as an addict has no chance of being rehabilitated and will be back inside having reoffended to feed the habit and clogging up a prison system already falling apart at the seams."