Bangladesh rescuers said Wednesday at least 550 people likely died in the collapse of a garment factory complex last week as the pope condemned the use of "slave labour" in the local clothing industry.
As bulldozers and cranes worked to remove the rubble of the eight-storey building on the outskirts of Dhaka, a senior army officer said the number of confirmed dead stood at 411 while around 140 people were still missing.
The impoverished nation's worst industrial accident, which has focused attention on hazardous conditions in Bangladesh's factories making Western labels, brought tens of thousands of protesters onto the capital's streets.
Workers holding red banners shouted "Hang the killers, Hang the Factory Owners!" during a May Day rally that was largely peaceful unlike larger and more violent protests staged since last Wednesday's disaster.
At the Vatican in a private mass, Pope Francis weighed into the controversy, speaking out against labour conditions in Bangladesh that have been decried by campaigners.
"A headline that really struck me on the day of the tragedy in Bangladesh was 'Living on 38 euros a month'. That is what the people who died were being paid. This is called slave labour," the pope was quoted by Vatican Radio as saying.
In fact, wages are even lower, with the legal minimum salary routinely paid to employees only 38 dollars (29 euros) a month for a six-day week with 10-hour shifts.
The Bangladesh government faces growing foreign pressure to take action to improve conditions in the garment industry, with the collapse at the Rana Plaza factory complex only the latest in a string of deadly disasters.
A textile factory blaze last November claimed 111 lives, and there have been widespread accusations that
safety standards are both too lax and rarely enforced in the $20-billion sector.
The European Union said late Tuesday that it would look at steps to promote better practices after a host of European retailers including Primark, Benetton and Mango admitted using factories in the collapsed building.
Nearly 60% of Bangladesh's garments are shipped to the European Union free of duties and tariffs, giving the 27-nation bloc a huge say over workplace safety issues in Bangladesh.
Anger in Bangladesh remains palpable and the demonstrations on Wednesday again saw demands for the building owner and four factory bosses who have been arrested to face execution. They have been charged with death due to negligence.
"We want the severest punishment possible for those responsible for this tragedy," Kamrul Anam, head of the Bangladesh Textile and Garments Workers League, told AFP.
"The government should hang the building proprietor and the factory owners. We want justice for these murders," said Liakot Khan, another of those taking part in the Dhaka protest, which echoed to the sound of drums and horns.
Police put the number of protesters at the main Dhaka rally at over 20,000, and there were smaller protests elsewhere in the capital and in other cities.
Many of the country's 4,500 garment factories have been closed since last Wednesday, a major blow for the economy which depends on garments for 80% of its exports.
At a government graveyard in the capital, 2,000 people looked on as 32 bodies unclaimed by relatives were buried in an unmarked mass grave close to the graves of victims from the November factory fire.
In a dramatic moment, the sister of one victim identified her sibling's body minutes before it was to be lowered into the ground. She took the body away to be buried separately by the family.
At least 411 people have been confirmed dead since the building collapse on April 24, army spokesman Lieutenant Mir Rabbi told AFP. More than 2,430 people have been rescued alive.
Speaking to parliament Tuesday night, Prime Minister Sheikh Hasina had urged employees to return to work and criticised reported attacks on some factories.
"I would like to tell the workers to keep their head cool, keep mills and factories operative, otherwise you will end up losing your jobs," she said.