The PSNI has said lives and property are being put at risk as a result of a series of incendiary devices being placed in major retail outlets before igniting and causing widespread damage.
Shoppers and retailers have been asked to be extra vigilant in the days ahead.
The discovery of five devices across four cities in the past three days has increased fears that a concerted campaign orchestrated by dissident republicans and designed to cause havoc in the Christmas shopping rush is gathering momentum.
The latest attack took place at the Poundstretcher shop in Newtownabbey, on the outskirts of north Belfast, shortly before midnight.
The blaze follows a major fire at the B&Q superstore at the Sprucefield retail park on the main Dublin/Belfast road yesterday morning.
It took more than 100 firefighters several hours to get the blaze, which started in the rugs department, under control.
Two other devices have been found in Derry and Newry. The blaze in Derry is estimated to have caused £100,000 worth of damage.
Business owners and keyholders have been urged by police to maintain regular checks on their premises.
