DHAKA (Reuters) - The death toll from a fire at a food and cigarette packaging factory in Bangladesh rose to 29 on Sunday as fire crews began digging through debris, and the number of fatalities could rise with over half a dozen people still missing.

People stand on a bridge as a firefighter truck drives at the site of a fire at a packaging factory outside Dhaka, Bangladesh, September 10, 2016. REUTERS/Mohammad Ponir Hossain

Thick plumes of smoke, pockets of fire and a partially collapsed building stalled search efforts, after a blaze that began early on Saturday swept through a factory making packaging material for local and international companies.

“There are still flames here and there as there are a lot of chemicals in the factory,” senior fire service official Masudur Rahman told Reuters.

Saturday’s blaze was the country’s worst industrial accident since the Rana Plaza building collapse of 2013 that killed 1,135 garment workers, and raises further questions about Bangladesh’s safety record.

“We do not know when the search will be completed as it is a huge task,” said Ajit Kumar Bhoumik, a senior fire department official. “We need more excavators and trucks to clear debris. We also need more manpower and other resources.”

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.

The blaze at Tampaco Foils plant broke out just as workers prepared to swap shifts in the early hours of Saturday morning.

PLANT “CONGESTED”

One former customer of the factory said Tampaco had been expanding production capacity to meet rising orders, but it “had not taken up more space, so the plant was congested.”

The factory is owned by Syed Mokbul Hossain, a former member of parliament. He told Reuters on Saturday that Tampaco was “fully compliant”. He could not be reached by telephone to answer further questions on Sunday.

Mikail Shipar, government secretary with the ministry of labor and employment, told Reuters the government was going to investigate safety at all of the hundreds of factories in the Tongi industrial zone.

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“We checked the design of this factory and initially it is our understanding that it was a one floor building and later the floor had been raised, similar to (the) case of Rana Plaza,” he said.

Shipar added that an investigation would be carried out and if anyone was found guilty of negligence, action would be taken.

“I have already been asked to formulate a project to inspect all the factories in all four industrial zones in the country,” he said. The location of the boiler in the building was also being scrutinized.

“Stern action will be taken against those responsible for the fire,” Industries Minister Amir Hossain Amu told reporters on Sunday, after visiting the scene. “No one will be spared.”

RENEWED SCRUTINY

The fire is the latest in a series of industrial accidents in the South Asian country, which is the world’s second biggest garment exporter behind China.

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

Two international coalitions have been formed to help fund improvements to building and fire safety at thousands of garment factories across Bangladesh.

One official on Saturday said that the government’s focus so far had been mainly on garment factories, and less on other industries, but that was now likely to change.

Tampaco Foils makes packaging for food and cigarettes for a number of local players and global brands like British American Tobacco BATS.L, Nestle NESN.S and Nabisco Biscuit & Bread - a unit of food giant Mondelez International MDLZ.O.

The three multinationals were not immediately reachable for comment.

A spokesman for Bangladeshi food giant Pran, also a customer of Tampaco’s, said the factory used to supply it with flexible packaging materials for snacks and confectioneries, but that it did not package finished products for them.

“After this fire we will meet our other suppliers and review their safety measures as well,” said the spokesman. “Our supply management team does routine visits to all our suppliers’ plants and we will strengthen these more now.”