Fr Dermot Maloney required hospital and dental treatment after he was attacked by the gang in Jonesborough, Newry.
He sustained facial injuries including a split lip and damage to his teeth.
At
around 11.30pm on Wednesday the priest discovered three youths in the
office before they assaulted him and left him locked in a bathroom.
They made off with his wallet containing a small sum of cash.
The priest managed to escape from the bathroom by climbing from a window.
Fr Maloney was too distressed to comment.