DHAKA: A police case has been filed against the owner of Tampaco Foils and several others working at the food and cigarette packaging plant near Dhaka as the death toll from a fire at the factory over the weekend rose to 31 on Monday.

The blaze erupted early on Saturday resulting in Bangladesh's worst industrial accident since the collapse of the Rana Plaza building in 2013 that killed 1,135 garment workers. It also raised renewed questions about industrial safety in Bangladesh, one of the world's top garment exporters.

"Police have filed a case in relation to the fire in which 31 people have so far died," said Farid Ahmed, deputy inspector general of the country's factory inspection department.

A police official said the case had been filed by the family of one of the victims. Officials expect more cases to be filed against the owner, whom police are still trying to locate, and others when courts re-open after the week-long Eid holiday.

Jahirul Islam, a director with the fire service department, told Reuters on Monday the Bangladeshi army had joined search efforts. "We need to move a huge amount of debris otherwise searching is not possible," he said.

Many fear the death toll could rise further as close to half a dozen people are still missing after the blaze caused a partial collapse of the factory building.

The cause of the fire in the Tongi industrial zone about 20 km (12 miles) north of the capital, Dhaka, was not immediately known, but officials said a gas line leak and a boiler explosion probably triggered it.