Acting Chief Executive Eric Chan on Monday said the police will thoroughly investigate the cause of an industrial accident on Austin Road over the weekend, which resulted in the death of two workers.

The duo went underground to repair the pipelines near the Elements shopping mall on Saturday morning, and were meant to finish work in the afternoon on the same day.

However, they never reemerged and were found dead at the underground site on Sunday, apparently due to methane gas poisoning.

The victims’ families questioned whether negligence was at play, after media reports suggested that a project manager had left the construction site on Saturday morning without completing the necessary safety checks, leaving the two workers locked underground for over 12 hours.

The acting CE said the police will conduct a criminal probe into the tragedy.

"We do have clear laws and guidelines on how to work in a closed environment. The most important thing is for employers to take responsibility and act conscientiously. If it's found that the casualties were caused by serious negligence, employers need to bear criminal responsibility,” Chan said.

He added that the Labour Department will inspect enclosed areas at construction sites across Hong Kong to ensure safety.