As two construction workers stood upon a scaffolding, it gave away and plunged the Hong Kong workers 56 storeys down, fire authorities said.

The pair was busy renovating a residential building in the upscale Mid-Levels neighborhood of the former British colony, one of the world's most vertical cities known for its strong safety record, when the fatal accident occurred, Agence France-Presse reported.

"When fire officers arrived, the gondola (suspended scaffolding) at the 56th floor was broken. Half of it had fallen to a platform around five or six storeys from the floor," a Hong Kong Fire Services Department spokesman told AFP.

The victims, one male and one female, were confirmed to have been construction workers. However, the spokesman could not confirm any more information on their identities.

"We located one dead person on the platform and the other person was found dead at a drain nearby," he said, adding that a man on the ground sustained injuries to his hands when struck by falling debris.

According to AFP, the incident is being investigated by the police of Hong Kong.

Last year, 24 construction workers died at their jobs, according to the Hong Kong Federation of Occupational Safety and Health Associations.

The group's president Victor Kwong said the safety of construction workers is an area of "growing concern" since construction-related accidents have proven to be fatal for eight people this year.

"There is more and more renovation work in Hong Kong which has many old buildings. The safety regulations are in place but are not always enforced," he said.

Safety procedures and awareness at work, including practical training for employees needed to be improved, Kwong said.

"We're very concerned about this very serious accident which resulted in two deaths," Matthew Cheung, Hong Kong Labor Minister, told reporters, conveying his condolences to the families of the deceased workers.