Police received a report of a fire at a council store in the Albert Basin area of Newry around 6pm on Friday 28 May.
Sergeant Cathy MacDonald said: “As the building is used only as a storage facility, there were no staff present at the time of the incident. We believe that the fire was started deliberately, with significant damage caused to the roof and interior.
“A police investigation is ongoing and I would appeal to anyone who saw unusual or suspicious activity in the area on Friday morning or afternoon, to get in touch with police on 101, quoting the reference number 1641 of 28/5/21.
“A report can also be made online using the non-emergency reporting form via http://www.psni.police.uk/makeareport/You can also contact Crimestoppers anonymously on 0800 555 111 or online at http://crimestoppers-uk.org/ “