DHAKA: Police in Bangladesh have filed charges ranging from negligence to murder against more than a dozen people after a boiler explosion at a garment plant killed 13 people and injured dozens, officials said on Wednesday.

Monday's blast happened during maintenance work at a factory owned by Multifabs Ltd, whose top buyers include fashion chain Lindex, which is part of Finland's Stockmann, German supermarket chain Aldi, and Rexholm of Denmark.

Police have blamed the accident on three boiler operators killed in the explosion on the outskirts of Dhaka, the capital, and 10 unidentified people.

"They have been accused of negligence and murder as they continued to operate the boiler, ignoring safety concerns," said Aminul Islam, chief of the police station investigating the incident.

Survivors found guilty could face punishments ranging from life imprisonment to the death penalty, authorities said.

Preliminary investigations showed the licence for the boiler had expired on June 24, district administrator Dewan Muhammad Humayun Kabir told Reuters.

The company said it had applied to renew the licence before the deadline, however.

"We applied to the authorities for renewal on June 15," company chairman Mahiuddin Faruqui told Reuters. "There was no negligence on our side."

The accident took place as the plant was being readied to resume operations on Tuesday, following a 10-day closure for the Eid al-Fitr holidays at the end of the Muslim holy month of Ramadan.

A boiler warning light was flashing before the explosion, but the maintenance team ignored it, said one survivor, Harunur Rashid, a worker in the garment dyeing process.

"We heard strange sounds two or three times, but we were told it was nothing," Rashid, hurt in the head and legs by the blast, said from his hospital bed. "Shortly after, it exploded."

The blast happened when workers sought to restart the boiler after servicing, Faruqui said.

"We don't know whether it gave any warnings or not," he added.

Bangladesh's roughly $28-billion garment industry, the world's biggest after China, employs 4 million people and generates about 80 percent of export earnings.

It came under scrutiny after the 2013 collapse of the Rana Plaza factory complex that killed more than 1,100 people, and a 2012 fire at a garment factory that killed 112 workers.

The Rana Plaza disaster sparked demands for greater safety and put the responsibility to act on foreign companies sourcing clothing from Bangladesh.