The warder was detained by detectives from the PSNI’s Reactive and Organised Crime Branch as part of a covert surveillance operation.
He was detained under the 1971 Misuse of Drugs Act.
The PSNI said in a statement tonight that detectives from Reactive and Organised Crime Branch, working in conjunction with the NI Prison Service, say they have arrested five people and seized a quantity of cash and drugs as part of an investigation into trafficking of prohibited items into Maghaberry Prison.
A 50-year-old prison officer was arrested this morning at Maghaberry Prison on suspicion of conveyancing prohibited articles into a prison, misconduct in public office, possession of criminal property and being concerned in the supply of Class A Drugs following a joint operation with the Prison Service.
He has been taken to Musgrave Police Station for questioning.
Four further arrests were also made today and three properties were searched in Newtownabbey, Belfast and Kinallen as part of the ongoing investigation.
A man aged 28 and a woman aged 26 were arrested in Newtownabbey on suspicion of conveyancing prohibited articles into a prison.
The 28 year old male was also arrested for possession of a Class B controlled drug and possession of fireworks.
A 55 year old woman was arrested at an address in Belfast on suspicion of possession of a Class B controlled drug, possession of a class B controlled drug with intent to supply, possession of criminal property, and conveyancing prohibited articles into a prison.
A 50 year old woman was arrested in Kinallen on suspicion of possession of a Class A controlled drug and possession of criminal property.
They have all been taken to Musgrave Police Station for questioning.
PSNI’s Head of Reactive and Organised Crime Chief Superintendent Tim Mairs said: “Detectives today seized £10,000 cash, a quantity of suspected Class A and Class B contolled drugs and a number of mobile phones.
“This operation is a good example of how collaborative working can disrupt crime and also demonstrates our commitment to Keeping People Safe by removing harmful drugs from society.
Head of the Prison Service, Ronnie Armour, said: “I welcome the result of today’s joint operation with the PSNI and would take this opportunity to reiterate the zero tolerance drugs policy which operates within Northern Ireland’s prisons.”
Maghaberry prison has been awash with drugs for year, with inmates boasting they can buy any drug they want.
Prescription drugs are the most sought after among prisoners.