It happened in Queen Street outside the building site cabin on Friday, February 3, around 9am. It is believed three unknown men removed the digger, a dark-coloured Atlas Copco digger, and loaded it into a white van before driving off.
Police are appealing for witnesses and anyone who was in the area and who may have seen or heard anything suspicious is asked to contact police. Officers also want to speak to anyone who may have been offered the digger for sale.
Anyone with information should call police on 101, quoting reference number 764 of 03/02/17, or ring the independent charity Crimestoppers on 0800 555 111.