A group of five or six teenagers were seen to spray paint graffiti on the side of Morris Bros, High Street, Tenby, sometime between 2.20 and 2.25 pm on April 20.
The words 'Ashby' and '2006' were sprayed on the building and anyone with information is asked to contact PC1033 Boorman at the town's police station on 0845 330 2000.