In the latest incident, a masked man walked into the Spar on Antrim Road, Belfast and set light to Sunday World newspapers.
The attack caused extensive smoke and water damage to the store and stock worth thousands of pounds was destroyed.
The Sunday World has angered loyalist paramilitary groups by its editorial line. An assistant said the store had been threatened over selling the paper, while other outlets in the area have stopped stocking it.
A police spokesman advised retailers in the area to check their security.