A viable letter bomb has been discovered at a postal sorting office in Derry.

Police confirmed the device found in the Great James Street facility yesterday afternoon was viable.

It was contained in a white A4 envelope with the address written in grey using a stencil.

Stormont's Justice Minister David Ford condemned those responsible, calling it a "cold blooded attempt" to cause death or serious injury.

He said: "Those behind this device do not care who they hurt or injure and have nothing positive to offer.

"I would ask people to continue to be vigilant and report anything suspicious to the police."

Last month, a series of letter bombs sent to army recruiting offices in England were blamed on dissident republicans opposed to the peace process.