At least 13 people were killed and nearly 20 people were critically injured when a fire swept through an illegal plastics factory outside the Bangladeshi capital Dhaka, police said Thursday.

Factory fires are common in Bangladesh, especially in the dry winter season, due to lax enforcement of safety codes.

The blaze started on Wednesday afternoon and quickly ripped through the ground floor of the Prime Patent Plastic factory in Keraniganj, just southwest of Dhaka, police said.

"So far 13 people were killed. Twelve of them died while being treated at the Dhaka Medical College Hospital and and another died at the scene," police inspector Bacchu Mia told AFP.

Police said some 150 people were working in the tin-shed ground floor factory when fire broke out with a loud bang in one of the rooms.