A prison officer in the Republic of Ireland was being questioned by gardai last night after being linked to two Christmas drug "selection boxes" destined for Mountjoy Prison.
The latest find was made in the officer's car, which had been parked at the rear of the prison.
It followed the discovery of packs of drugs, which had been strapped to his leg, as the officer was being routinely searched by colleagues on his way into work yesterday morning.
The initial haul included 450 grammes of cannabis resin, which had a street value of around ?2,250 but would probably fetch up to ?4,500 in the prison because of the recent clampdown on drugs.
The cannabis was divided up into two packs of 200 grammes each and one 50 gramme pack.
Also recovered were small quantities of heroin and cocaine, some cannabis herb, 400 tablets, known as D10s, which can be bought on prescription to treat a range of conditions including alcohol withdrawal, anxiety and tension, and 300 steroid tablets.
The officer, in his 30s, was being routinely checked as he turned up for work at around 7.30am when staff selected him for a more thorough search and found the drugs stash.
Prison authorities immediately contacted the gardai and the officer was taken for questioning to nearby Mountjoy station where he was still being held last night.
gardai can hold him for a maximum of 24 hours to detain him without charge, including rest periods.
One investigator said last night: "This appears to have been a Christmas selection box of drugs that was intended for sale to the inmates in Mountjoy.
"The amount of drugs in the jail has dropped dramatically since a tougher regime was introduced by new governor Ned Whelan and these packs would have fetched a lot more than street prices," he said.
After the arrest gardai carried out further searches in the officer's vehicle in the nearby car park and at his Dublin home.
Inside the car gardai found a similar selection of drugs, which were estimated to have a street value of around ?5,000.
The Prison Officers Association said last night it would not support any officer, who, for whatever reason, became involved in drug trafficking.
While not commenting specifically on the finds, the association said the actions of the few could bring disgrace and embarrassment to all of the hardworking prison officers around the country, who did not tolerate or take part in any illegal activity.