At least 44 people were killed and dozens injured after a fire blazed through a seven-storey building in an upscale neighbourhood in the Bangladeshi capital of Dhaka late Thursday, authorities said.

"So far 43 people have died from the fire," Bangladesh's health minister Samanta Lal Sen told AFP after visiting the Dhaka Medical College Hospital and an adjoining burn hospital.

Police inspector Bacchu Mia said one more person died at Dhaka's main police hospital to bring the death toll to 44.

Sen said at least 40 injured people were being treated in the city's main burn hospital.

"None of them are out of danger," he told AFP.

Fire department official Mohammad Shihab said the blaze originated in a popular biriyani restaurant in Dhaka's Bailey Road at 9:50pm Thursday (1550 GMT), and quickly spread to the upper floors, trapping scores of people.

Firefighters brought the blaze under control in two hours, he said.

They rescued 75 people alive, a statement from the fire service said.

Fire officials told reporters they suspected the inferno was caused by a gas cylinder blast at the restaurant.

"It raced through the upper floor quickly as there were restaurants in almost all floors of the building. They use gas cylinders," one fire officer, who did not give his name, said.

The government has ordered a probe into the incident.

The Bailey Road building houses mainly restaurants along with several clothing and mobile phone shops.

"We were at the sixth floor when we first saw smoke racing through the staircase. A lot of people rushed upstairs," said a restaurant manager called Sohel.

"We used a water pipe to climb down the building. Some of us were injured as they jumped from upstairs," he said.

Others were trapped on the rooftop and called out for help.

"Alhamdulillah (praise be to god). We are sending down all women and children including my wife and children. We all men are in rooftop. Fire service stands beside us. Fifty yet to be down," wrote Kamruzzaman Majumdar, a professor of environmental science, in a Facebook post.

He was later rescued safely.

Hundreds of anxious family members rushed to the Dhaka Medical College Hospital as ambulances brought the dead and injured to the clinic.

Fires in apartment buildings and factory complexes are common in Bangladesh due to lax enforcement of safety rules.

In July 2021, at least 52 people were killed including many children when a fire swept through a food processing factory.

In February 2019, 70 people died when an inferno ripped through several Dhaka apartment blocks.