The Ministry of Manpower (MOM) has suspended all cleaning works for the facade of Republic Plaza in Raffles Place after four workers were spotted swinging precariously on a gondola last Wednesday.

An MOM statement yesterday also said the ministry is investigating the incident.

A spokesman for Republic Plaza's building management told The Straits Times yesterday that four workers from its appointed cleaning contractor were on a gondola when "unexpected strong winds" caused it to sway while ascending from level 50 to the rooftop.

"Due to weather conditions, this can occur from time to time," said the spokesman. Once the management was notified of the situation, the external cleaning works were stopped as the "workers' safety is our top priority", he added.

The gondola had been certified safe to operate and the workers were trained and certified to perform facade cleaning at height. The workers on the gondola also had personal protective equipment, he said. No one was injured.

The contractor has been doing regular facade cleaning at the 66-storey Republic Plaza since the early 2000s, said the spokesman.

The building management is working with MOM to look into the matter and explore ways to further minimise swaying of the gondola due to unexpected changes in weather conditions.

Witnesses told citizen journalism website Stomp on Monday that four men were standing on the gondola 58 storeys high at about 2.30pm, when it slammed into a glass window a few times.

Videos show the workers repeatedly looking upwards as the gondola sways. They are also seen holding onto the sides of the gondola and trying to stabilise themselves. As the gondola nears the window, one of the workers is seen pushing his hand against the facade. The men appear to have cleaning equipment with them.

A witness, who gave her name only as April, said: "These brave men mustered a smile despite being clearly petrified each time the gondola slammed into the building... It was scary watching this."