An unattended bag had been found on the ground floor of the building as most office workers were having their lunch break.
As a safety precaution, the Monetary Authority of Singapore alerted police, who investigated the bag before giving the building the all clear at 3pm.
Eyewitnesses told Channel NewsAsia several police cars and army vehicles were at the scene.
And while workers were not evacuated, parts of the building were cordoned off. "The security did not let us go in. He said there was a bomb scare over there so we delayed until about 10 minutes then they let us go up," said Owyeong Khai Cheong of MAS' banking and computer services division.
Workers at the construction site next door did not hear any loud commotion but they saw many people gathering.
"I see just across the road there was a police car and army, a bomb unit came in. So they fence up the area and people started to walk around and see what's happening. Even the bank staff - everybody was talking," said Eric Sim, the manager of a cafe at nearby Internationl Building.
The police would only say security operations were in progress at the MAS building from 12.56pm to 3pm.
But in the light of the recent international watchfulness over terrorist attacks, this incident has been a talking point among office workers in the area.