A dairy in Christchurch has been targeted by cartoon-mask wearing robbers twice in past month, police say.

The most recent incident at the Union Street dairy in New Brighton happened on Wednesday about 6.45pm.

A man wearing a 'joker' type mask demanded money from the dairy staff before fleeing on foot, empty handed, police said. He was described as 172cm tall, slim to medium build, in his 20s and was wearing a burgundy hoodie, black trousers and grey beanie over a rubber/plastic 'joker' mask.

The attempted theft followed a similar incident on April 4 where shortly after 12pm a person of above average height wearing a fluoro orange sweatshirt and a distinctive cartoon mask demanded money and fled the scene with a quantity of cash.

CCTV image from Union Street Dairy May 6. Photo / New Zealand Police
CCTV image from Union Street Dairy May 6. Photo / New Zealand Police

No one was injured in either incident but police were keen to hear from anyone who might recognise the people in the CCTV photographs or witnessed anyone fleeing the dairy after the incidents.

It was too early in the investigations to confirm whether or not the incidents were linked, police said.

Anyone who could provide information to help identify the two offenders should call Canterbury police on 03 363 7400 or anonymously to Crimestoppers on 0800 555 111 and quoting 'Union Street dairy robbery'.