Business owners in Northern Ireland are being urged to regularly check their premises after recent firebomb attacks.
An incendiary device was left at the Homebase store last month
Dissident republicans have been blamed for a series of such attacks in Belfast, Newry and Coleraine.
Police are urging shop staff to carry out checks during trading and at the end of the working day.
A spokesman warned incendiary devices could destroy property and kill. He said devices could be found hidden in garments, furnishings or upholstery.
On Friday, Northern Ireland Secretary Peter Hain revealed that attacks carried out by dissident republicans had cost more than £25m in just seven months.
Mr Hain said the damage was caused to commercial premises across Northern Ireland.
A spokesman for the Police Service of Northern Ireland (PSNI) said: "It is extremely important that those involved in business carry out a thorough search of their premises prior to locking up for the evening, or the weekend.
"At this time of year when shops and shopping centres are particularly busy we would urge extra vigilance.
"Anyone who witnesses any suspicious activity should contact police. And anyone who finds anything suspicious should leave it alone.
"Members of staff should not touch or move any suspicious looking objects but rather contact police immediately."
Dissident republicans have been blamed for recent firebomb attacks on a number of stores in Belfast.
The Homebase store on Boucher Road was destroyed in one attack last month, while nearby Smyth's toystore was also targeted.
JJB Sports in Anne Street in the city was badly damaged in a third attack on the same day.
Last month, dissident republicans were blamed for a fire bomb attack on a B&Q store in Coleraine.
The Real IRA was also blamed for a series of incendiary attacks on commercial premises in Newry in August.