MOBILE phones and cannabis have been uncovered in a planned search operation at Mountjoy Prison.
The intelligence-led search smashed a regular supply route of contraband into the prison involving trustee prisoners.
Their duties include cleaning the various landings and in this role some have greater access to parts of the prison and greater freedom of movement than other inmates.
Today, the Prison Service confirmed that five mobile-phones had been found on Monday night -- as well as phone chargers -- with cannabis resin discovered in a follow-up search.
A prison source said there are up to 50 prisoners engaged in cleaning work.
"Some have greater access to certain areas. For example, they may have access to an area where mobiles may have been thrown over the wall by arrangement."
It is understood that two prisoners have been quizzed about the finds and may face transfer to another prison and charges before the District Court.
Gardai at Mountjoy station will examine the phones to establish the communication traffic on the lines.
The searches were carried out as it emerged that almost five mobile phones a day were found on average in Irish prisons last year.
The total discovered during the year was 1,718, with Mountjoy topping the list at a staggering 742.
In 2009, a total of 2,174 phones were found, compared with 2,047 in the previous year.
Practically all the country's institutions had fewer mobiles found in 2010 than in previous years, with Mountjoy Prison's figure down from 904 in 2009.
In the latest figures, recorded in the Irish Prison Service annual report, only one phone was seized in Arbour Hill, where the inmates are generally sex offenders.
The Training Unit recorded 191 seizures last year, up from 116 in 2009, while St Patrick's Institution recorded 138, up from 121.
Limerick had 133, while the open prison Loughan House had 155, twice the previous year's figure of 78.