Palmerston North Police are investigating two separate aggravated robberies at city supermarkets on the evening of 23 December 2012.
Detective Sergeant Ashley Gurney said: "In the first incident, at about 9:20pm a disguised offender has attempted to enter Countdown Supermarket in Kelvin Grove armed with a weapon."
"A security guard has intervened and then been struck by the offender using a sharp object, leaving the security guard with a small laceration."
The offender ran from the supermarket and was seen getting into a dark two door motor vehicle.
At about 9:40pm a disguised offender has entered Countdown Broadway and threatened staff there using a sharp object.
The offender obtained cash and exited the store. No person was injured during this aggravated robbery.
"Police have launched enquiries into each matter and are looking for assistance from the public. We are seeking witnesses from each of the supermarkets and are not ruling out the possibility that the two matters are linked.
"We encourage anyone who has any information to contact the Palmerston North Police Station on 06 351 3600 or alternatively Crimestoppers on 0800 555 111."
Media enquiries should be referred to Detective Sergeant Ashley Gurney on 027 290 0460.