An air-conditioning servicing and maintenance worker befriended a cleaner at a Shenton Way building where both worked.
One day, Uddin Mohammed Shahab, a Bangladeshi, beckoned the 28-year-old woman towards a service room on the seventh storey and outraged her modesty.
Uddin, 45, was jailed for six months yesterday after pleading guilty to a molestation charge.
The court heard that the cleaner was waiting for a cargo lift on the 14th storey at around 10am on April 18 when she met Uddin.
Deputy Public Prosecutor Rebecca Wong said Uddin and the woman had spoken to each other a few times previously.
They took the lift down and she got out on the seventh storey to carry out her cleaning duties.
Uddin initially remained in the lift but later followed her.
DPP Wong said: "Suddenly, the accused appeared before the victim and beckoned her towards the service room... by saying 'come lah'. ''
"The victim, thinking that the accused wanted to enter the service room and confused as to why she needed to follow him to the service room, stepped aside. This caused her to back into a wall."
Uddin tried but failed to unlock the door. He then grabbed the cleaner's chin and touched her breast before walking away.
"The victim, shocked at what had happened, stood in the same place until a co-worker approached her," said the DPP. She then told her co-worker what had happened.
The victim later also told her supervisor about the incident and made a police report on May 2.
For outraging the woman's modesty, Uddin could have been jailed for up to two years and fined or caned.