Bangladesh authorities accused a container depot operator on Monday of not telling firefighters about a chemical stockpile before it exploded with devastating consequences, killing at least 49 people — nine of them from the fire service.

The toll from the giant blast, which followed a fire at the BM Container Depot in Sitakunda and sent fireballs into the sky, was expected to rise further.

Some containers at the depot were still smouldering on Monday, more than 36 hours after the explosion, preventing rescuers from checking the area around them for victims.

Around a dozen of the 300 injured were in critical condition.

The nine dead firefighters are the worst toll ever for the fire department in the industrial-accident-prone country, where safety standards are lax and corruption often enables them to be ignored.

“The depot authority did not inform us that there were deadly chemicals there. Nine of our officers were killed. Two fighters are still missing. Several people are also missing,” fire department official Mohammad Kamruzzaman told AFP.

Purnachandra Mutsuddi, who led the fire-fighting effort at the 26-acre facility on Saturday night, said it “didn't have any fire safety plan” and lacked firefighting equipment to douse the blaze before it turned into an inferno.

“The safety plan lays out how the depot will fight and control a fire. But there was nothing,” Mutsuddi, an assistant director of the Chittagong fire station, told AFP.

“They also did not inform us about the chemicals. If they did, the casualties would have been much less,” he said.

The BM Container Depot in Sitakunda, an industrial town 40 kilometres from Chittagong Port, is a joint venture between Bangladeshi and Dutch businessmen with around 600 employees, and began operations in 2012.

Its chairman is named on its website as Bert Pronk, a Dutch citizen, but AFP was unable to reach him for comment. Few European businessmen operate in the country.

Local newspapers said another of its owners is a senior official of the ruling Awami League party based in Chittagong, who is also the editor of a local Bengali daily.

Police have yet to lay charges over the fire. “Our investigation is going on. We will look into everything,” said local police chief Abul Kalam Azad.

Prime Minister Shehbaz Sharif has expressed grief over the loss of lives in the incident and extended his condolences to the people of Bangladesh.

“Sad to hear about the loss of precious lives in a fire incident in Bangladesh. My heartfelt condolences & most sincere sympathies are with the government and people of Bangladesh,” he said in a tweet.

'Falling like rain'

Wisps of smoke rose into the bright morning sky from dozens of 20-foot containers at the depot on Monday.

“Some 30 to 40 containers are still smouldering,” said fire department inspector Harunur Rashid. “Fire is under control. But chemicals are main problems.”

Once the flames are entirely out, rescuers will search the area for more victims, he said.

Mujibur Rahman, a director of BM Container Depot, said the cause of the initial fire remained unknown.

The container depot held hydrogen peroxide, according to fire service chief Brigadier General Main Uddin, and witnesses said the entire town shook when the chemicals exploded.

“The explosion sent fireballs into the sky,” said Mohammad Ali, 60, who runs a nearby grocery store. “Fireballs were falling like rain.

“We were so afraid we immediately left our home to find refuge,” he added. “We thought the fire would spread to our locality as it is very densely populated.”

Elias Chowdhury, the chief doctor in Chittagong, said doctors at multiple hospitals had been called back from holidays to help treat the hundreds of injured.

Around 90 per cent of Bangladesh's roughly 100 billion dollars in trade — including clothes for H&M, Walmart and others — passes through the Chittagong port at the top of the Bay of Bengal.

Rakibul Alam Chowdhury from the Bangladesh Garment Manufacturers and Exporters Association (BGMEA) said that about 110 million dollars worth of garments were destroyed in the fire.

“It is a huge loss for the industry,” he said.