A controlled explosion was carried out on the suspicious object found outside the Alliance party office on the Upper Newtownards Road in east Belfast on Tuesday.
The object was discovered by a council worker on Tuesday morning but declared to be an elaborate hoax later that afternoon.
The man told the four staff members inside Naomi Long’s constituency office that he had moved a bag from a disabled ramp outside the building to a nearby bin but said there was something inside it.
The staff checked the bag and found a sweet tin and immediately called police who evacuated the office and cordoned off the area.
Ms Long, speaking from London, said the incident will not stop her working for her constituents.
“People may dismiss a hoax as something that is not serious but it still causes major stress and disruption, and whoever placed the object there knows that,” said Ms Long. “I have been elected to represent the people of east Belfast and I take my responsibilities in that job very seriously.
The Upper Newtownards Road was closed between its junction with Beersbridge Road and Grampain Avenue.
Assembly member Chris Lyttle said the incident was one of “reckless intimidation”.
“My colleagues and I will not be deterred from delivering for constituents and businesses by reckless intimidation and threat.”
In December Ms Long’s office was attacked with a petrol bomb while being guarded by police as the flag protests erupted following the vote to restrict the number of days the Union flag flies over Belfast City Hall.
Ms Long was also subject to a death threat during the disorder.
East Belfast MLA Robin Newton condemned those responsible.
He said: “Those responsible for planting this device have nothing to offer the people of East Belfast or Northern Ireland. Those living and working in the area have had their lives and businesses disrupted whilst the public were placed in danger.
“Any attempt to intimidate or disrupt through such security alerts must be condemned by all and a message sent that such tactics have always been wrong and can never be justified.’