Police fear dissident republicans are preparing a series of firebomb attacks.
Dissident republicans have been behind incendiary devices
The PSNI has urged business owners across NI, including retail parks, to check their premises for devices and look out for anything suspicIous.
The police have asked managers and staff to check on a daily basis for incendiary devices.
"Devices can be left in garments, soft furnishings, and upholstery, anywhere that can catch fire easily," said a spokesman.
"Business owners and staff must be observant and look out for anything suspicious. If something looks out of place, or even just raises concern, contact the local police.
"Members of staff should not touch or move any suspicious looking objects but rather contact police immediately."