A man was arrested in the Quay area of Ballina on Saturday night in connection with the theft of oil from a premises.
There was a mobile garda patrol car in the quay area when gardai observed a person in the process of stealing heating oil.
Gardai seized a vehicle parked close to the location and the vehicle contained a large amount of siphoning equipment and drums.
They arrested a man on suspicion of theft and he was questioned at Ballina garda station.
He was later released pending a file being prepared for the DPP.
Gardai in Ballina are appealing to the public, should they see anything suspicious or anyone acting suspiciously in the area to contact Ballina garda station at 096 21422.