The police are investigating an incident in Maghaberry after a female warder had a bin containing urine and excrement poured over her.
The attack happened in Maghaberry Prison
The Prison Service said the officer - who was with a male colleague - was attacked in Bush House, which houses loyalist paramilitary prisoners.
Both warders received medical treatment after the incident. Prison governor Alan Longwell condemned the attack.
"The attack was highly vindictive and particularly revolting," he said.
"It was calculated to cause maximum distress."
The prisoner has been transferred to the Special Supervision Unit and has been placed on Rule 32, restricting freedom of association.