The thief is described as Caucasian, short, about 162cm tall and aged between 19 and about 23 years. He was thin, wearing a black baseball cap and appeared clean shaven. He was dressed in a long sleeved top with no hood. The top sleeves were black and the rest of it was red. He was also wearing black pants and black shoes.
Ms Walker said police would be visiting businesses in the central business district to review closed circuit television footage from Friday night to assist with their inquiry.
Members of the public who had seen the person fitting the description of the offender or had witnessed the incident were urged to contact acting senior sergeant David Cross at the Greymouth Police Station.
Those with information also had the option of contacting police anonymously via the 0800 CRIMESTOPPERS phone line.
Ms Walker said the robbery - along with recent burglaries in the Greymouth central business district - highlighted the need for people to call police as soon as they saw any unusual activity or suspicious behaviour.
It also unfortunately served as a warning for people out and about at night, she said.
"Police also want to remind the public at night to be safe and call 111 if they see anyone or anything suspicious. We are continuing to patrol the CBD area regularly," Ms Walker said.
The Grey District Council has set aside money this year to renew crime prevention cameras in the downtown area.
It approved spending $15,000 for this financial year in the 2016-17 annual plan last month to renew or replace crime prevention cameras, some of which are currently out of commission.
Mayor Tony Kokshoorn said a recent anecdotal surge in burglaries and petty crime in the town was an unfortunate reminder for local people "to be more vigilant".
"There are a lot of people from outside the district coming here. However, although there's no statistical evidence of increases in burglaries, if the latest one on the street is indicating that, then it's a timely reminder," he said.
"A community that is on guard is a good deterrent," Mr Kokshoorn said.
- Greymouth Star