A 50-metre cordon was established by Gwent Police after the suspicious device had been found at the George Hotel in Moor Street just after 1pm.
Temporary diversions were put in place and some properties were evacuated as a precaution.
Specialist trained personnel from the army’s explosive ordnance disposal unit (EOD) also attended to examine the object.
After further examination, by the EOD, it was confirmed not to be dangerous and was taken away to be disposed of.
Chief Superintendent Tom Harding said: I’d like to thank the community for their patience and understanding as we worked with our partners to ensure the safety of everyone in the area.
The hotel confirmed it was a “small firework” that had been left in a room by a previous guest.