Police have released CCTV images of a man clutching a hammer who is wanted in connection with an aggravated robbery of a Christchurch service station.

Detective Sergeant Mike Freeman said the alleged offender entered the Challenge service station on Blighs Rd about 8.20pm last night. His face was partially obscured and he was armed with a claw hammer.

The man made away cigarettes and cash after threatening the attendant with the weapon.

He was described as wearing a distinctive black cap with a white logo and carrying a black backpack, also with a white logo.

He was last seen running down Blighs Rd toward Wairakei Rd.

Police want to speak to anyone who may have witnessed the incident, or who has any information about the man involved.

Anyone with information can call Detective Sergeant Mike Freeman on 03 363 7400, or contact Crimestoppers anonymously on 0800 555 111.