Two major roads, the Westway and the M1, were closed during the morning rush hour while police carried out a controlled detonation, the Belfast Telegraph reported.
Chief Superintendent Pauline Shields, the district commander, said police had to be careful.
"Had this been a viable device, there could have been devastating consequences had it exploded," she said. "Once again our community has been disrupted and the lives of residents put at risk by a cowardly element intent on causing as much disruption as they can."
In County Fermanagh, another suspected bomb in a beer keg left by the side of a road also proved to be a fake.
A security alert was called last Friday after a 60-kilogram device was found in an abandoned car in Fermanagh. While investigators believed it was intended for a nearby police station, a dissident republican group, Oglaigh na hEireann or Warriors of Ireland, said in a message the target was the Lough Erne golf resort 16 miles away where the Group of Eight summit is scheduled for June.