Bangladesh factory collapse: People trapped and deaths confirmed as emergency workers respond to Mongla cement factory incident

Facility run by subsidiary of the Bangladeshi army

A Bangladeshi survivor of the collapse of a partly-built cement factory in Mongla, lies on the floor of a hospital in Khulna on 12 March (AFP/Getty Images)

A five-storey cement factory has collapsed in Bangladesh, killing at least four people and trapping around 100 construction workers.

Rescuers said about 40 people had been pulled from the wreckage so far, with the majority requiring hospital treatment, but that there were 150 working on the factory at the time.

The cause of the collapse is under investigation, police said, though officials said it is believed that an under-construction section of the roof may have caved in.

Four deaths have been confirmed so far at the factory in Mongla,about 135 km (85 miles) southwest of the capital, Dhaka. Officials told a Bangladeshi news agency it was owned by an welfare organisation for the Bangladesh army, and soldiers and sailors in the port city were helping firemen with the search for survivors.

It comes amid the backdrop of continued concerns over building safety in Bangladesh.

A complex of shops and small factories collapsed in 2013 killing more than 1,130 people, most of them garment workers.

The collapse of Rana Plaza, built on swampy ground outside the capital, Dhaka, ranked among the world's worst industrial accidents and sparked a global outcry for improved safety in the world's second-largest exporter of ready-made garments.

Additional reporting by agencies