At least nine people have been killed in a fire at a garment factory in the Bangladeshi town of Gazipur, 40km north of the capital, Dhaka, emergency officials have said.

Those killed in the fire at the Aswad garment factory included the general manager, Rashiduzzaman Mandal, said fire official Zafar Ahmed.

He said the fire was doused early on Wednesday after firefighters laboured for 10 hours to bring it under control.

Local police chief Amir Hossain said most of the victims had been so badly burned that they could not be identified.

Factory director Emdad Hossain said 170 workers were inside the factory when the fire started and most were able to escape. Hossain said he suffered slight injuries himself.

Farhaduzzaman, another fire official, said the fire spread to two buildings that housed garment factories belonging to the Palmal Group of Industries.

A series of deadly incidents at Bangladeshi factories, including a building collapse in April that killed more than 1,100 people, have raised global concern over safety standards in the South Asian country's booming, $20bn garment industry.

The collapse of the building housing garment factories near Dhaka was the world's deadliest industrial accident since the 1984 Bhopal disaster in India.

Garments are a vital sector for Bangladesh and its low wages and duty-free access to Western markets have helped make it the world's second-largest apparel exporter after China.

The recent string of accidents has put the government, industrialists and the global brands that use the factories under pressure to reform an industry that employs four million and generates 80 percent of Bangladesh's export earnings.