More than 400 weapons and nearly 600 mobile phones were seized in Irish prisons in 2016 by the Operational Support Group (OSG) using on-site screening and dog units, it can be revealed.
The Prison Service analysis of statistics also shows that the OSG seized drugs on 660 occasions, as well as confiscating more than 300 litres of alcohol during the year.
A further 1,790 prohibited items were also recovered during more than 13,000 random searches and 66,000 visitor searches.
The success comes despite changes to the numbers and training protocols of the dog unit, which saw 16 'attack dogs' being removed from services in 2014 after a review of their role.
The dogs were all highly trained and based mainly in Dublin jails, including Mountjoy and Wheatfield, but some were also situated at the Midlands prison in Portlaoise.
Following an analysis of the use of the conflict resolution dogs and the potential use of that resource, it had been decided to "stand down" the animals immediately, the Prison Service said at the time.
The removal of the dogs has caused tension between the Irish Prison Service management and the unions who represent staff.
The results of a canine unit audit were received by the Irish Prison Service earlier this year and it remains to be seen whether any recommendations within it will aggravate or alleviate the differences of opinion between management and unions.
In May 2015 it was announced that more sniffer dogs were being trained to search out drugs and other contraband in Irish jails.
At that point in time there were only four active dogs and 24 additional dogs in operation, but management promised that the end of 2015 there would be 46 operational sniffer dogs in the Irish prison system.
But sources have told the Herald the number did not increase beyond 24.
In a letter to staff before Christmas, OSG governor John Farrell praised them for their work in often challenging times.
"The individual and collective role you all play in this cannot be under-estimated and is oft times not fully appreciated or recognised," he said in the letter.
"In 2016 you have all contributed to the screening of 186,537 visitors, prevented entry of and/or recovered 597 mobile phones, seized drugs on 660 occasions, confiscated 406 weapons, confiscated 341 litres of illegal alcohol, recovered a further 1,790 prohibited items in prisons, facilitated 97 arrests of suspect persons, conducted 13,471 random searches and 66,481 visitor searches.
"I wish to formally recognise the efforts taken in delivering these returns."
While the letter does not break down the statistics on a prison-by-prison basis, it does highlight that the canine unit "returned 1,326 interceptions, facilitated 10 arrests, dictated the screening of 610 visits and advised on the rescheduling or cancelling of 689 visits, all helping prevent contraband ingress".
The OSG was established by the Irish Prison Service in 2008 prevent contraband entering prisons.
The role of the OSG is to prevent the direction of crime from prisons and to detect prohibited articles within them.
This year it was announced by Justice Minister Frances Fitzgerald that up to 360 prison officers are to be recruited over the next three years.
It is the first time a recruitment campaign for prison officers has taken place since 2008.
The first recruits are scheduled to enter the Irish Prison Service College early next year. Those taking up the positions will enter as a recruit prison officer.