Police have closed the Ashgrove Road in Newry.
According to Newry and Armagh MLA Justin McNulty, a loud blast in the night is suspected to be an explosive device.
The SDLP representative said: “No one has been hurt thankfully and police are investigating.
“The area has been cordoned off once again and the council have kindly made Newry Leisure Centre available for any residents should they need it.
“This is the third time this dangerous disruption has happened and I know residents find this activity both frightening and infuriating. It must stop now.”
A PSNI spokesperson said the operation was ongoing.
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