Police in Bangladesh are investigating the death of a 9-year-old boy who was killed with an air compressor at a textile mill on Sunday.

The child, Sagor Borman, was attacked by co-workers at the factory in Narayanganj, on the outskirts of the capital Dhaka.

Police official Forkan Sikdar confirmed Borman died of internal injuries later that day.

"The boy died after other workers inserted a nozzle through his rectum. His father found his son lying beside a compressor machine with his abdomen swollen," he said.

Children under the age of 14 are not allowed to work in Bangladesh, but child labour is common - Unicef estimates 4.9 million children from five to 14 are currently working in hazardous conditions the across the country.

Rupganj police chief Ismail Hossain said they have made an arrest and were searching for others.

"We have arrested the mill's assistant administrative officer. We've also launched a hunt for others accused including three production managers who were named in the case", he added.