At least three workers have died and five others critically injured after an explosion at a Singapore workshop that left victims with their clothes torn off and badly burnt, reports said Thursday.

The men were taken to hospital Wednesday after the blast at a company that works on fire protection systems in an industrial area, the Straits Times newspaper reported.

Authorities did not respond to requests for comment.

Preliminary investigations found the accident was caused by a “combustible dust explosion”, the reports said.

The nationalities of the men was still unclear.

Singapore is home to hundreds of thousands of foreign labourers, many of them from South Asia, but industrial accidents are rare.