Police are hoping security cameras will help them identify a man who robbed a Christchurch dairy on Thursday night.
The man was recorded by security cameras in the Ilam dairy as he assaulted a staff member with a piece of wood.
Detective Constable Nathan Lean says the man demanded cash from the shop assistant before striking them on the head and shoulder. He left without taking any money.
Mr Lean says the shop assistant was treated by ambulance staff for minor injuries.
The attacker is described as a European, aged at least 18, with tattoos on his left forearm.
Police are appealing for anyone with information to contact them.