A part-time security officer was killed last year after he fell into a 4m-deep pit near the 1-Altitude rooftop bar at One Raffles Place.
A coroner's inquiry into Mr Shaun Tung Mun Hon's death revealed that the opening had been left uncovered by workers who were tasked with cleaning the building's facade.
Yesterday, a Ministry of Manpower (MOM) officer told State Coroner Kamala Ponnampalam that the workers had found moving the concrete slab to cover the opening on a daily basis "quite troublesome".
Barricades and warning signs had also been put up near the opening at an earlier time. But the MOM officer testified that these measures were "not effective".
The court heard that the ministry is contemplating action against the parties involved and that investigations are ongoing.
A concrete slab cover, weighing about 80kg, had been moved to expose an opening near the nightspot on June 9 last year.
The opening led to a pit and guests were barred from entering the area surrounding it.
Inside the opening was a switch to operate a gondola, which was used to clean the facade of One Raffles Place - a 63-storey building.
Workers tasked to perform the job had left the opening uncovered that day, the court heard.
Mr Tung, 26, a part-time security guard, was shown the pit and was briefed about it before he started his shift at the alfresco bar on June 9 last year.
Part of the second floor of the nightspot had also been cordoned off with barricades and warning signs. Despite this, two unidentified men entered the area at around 1.30am and Mr Tung spotted the pair. He ran towards the men while shining his torch to warn them but failed to spot the pit himself and fell in.
The court heard yesterday that there was no lighting in the area near the opening.
Mr Tung's colleagues saw him fall in and his supervisor, who rushed forward, saw him lying face down at the bottom of the pit.
Paramedics arrived at the scene and Mr Tung was pronounced dead about 30 minutes later.
The autopsy revealed that he died from a head injury.
Mr Tung, father to a young son, was cremated on June 11 last year.
State Coroner Kamala is expected to give her findings next Thursday.
