Rescuers and officials said they had retrieved 30 bodies from under rubble, and pulled out more than 100 people alive, after the nine-story garment factory building collapsed on Monday.
A similar number or more could still be trapped, civil volunteers said on Wednesday, but the stench of death wafting up from under the debris left rescuers and relatives with fading hopes.
"Is anyone there? Please say yes if you are alive," a rescue worker yelled, putting his mouth close to a hole in the ruins. No one responded, witnesses said.
Rescuers dug out four more bodies from the rubble overnight, and on Wednesday struggled to remove the mountainous pile of concrete slabs and bricks by cutting holes from the top and using sniffer dogs.
"Now we are trying to cut a passage to the fourth floor and then will strive to go to lower floors," said Brigadier-General Nizam Ahmed on Wednesday.
The army was coordinating efforts with police, firefighters and volunteers, he said.
"The operation is advancing as per plan, but the recovery is slow as we have to work very carefully so that no survivor is harmed," Ahmed said.
Two people were found alive late on Tuesday.
"I was working on the seventh floor when the building caved in and was trapped for more than 24 hours before I could see a flicker of light coming in," said Muhammad Motaleb.
Rescuers have found 30 bodies
in the rubble of the building
"My indomitable desire to live gave me strength, and eventually I could wriggle myself out," he said at the scene.
Also coming out to safety on Tuesday night was Palash, who goes by one name. He was working at the boiler room of the factory when an explosion there is thought to have brought the building down.
"I am delighted to be alive. It seemed unbelievable until I really made it," he said.
Rescue workers pumped oxygen and dropped water bottles through holes for presumed survivors.
"We are having a list of around 90 people still missing," said army Colonel Hanif Iqbal late on Tuesday.
The Shahriar Fabrics factory collapsed soon after midnight on Sunday. A planning official said the factory at Palashbari, 30km from Dhaka, had been built on marshland without planning permission.
Security officer Abdul Hye said on Monday that at least 250 people had been working the night shift at the factory, which is surrounded by marshes and paddy fields.
Bangladesh's garment industry employs nearly 2 million people, mostly women, and is notorious for poor safety standards.
Since 1990, nearly 300 garment workers have been killed and more than 2500 injured in 22 fires at factories triggering stampedes, according to industry officials.
Relatives fear the worst as they
await news about loved ones
On Wednesday, hundreds of mourning relatives stood around the collapsed building calling for loved ones.
The building's owner, Shahriar Sayeed Hossain, could not be contacted for comment. A statement issued by his office late on Monday said the victims would be compensated.
The factory produces clothes for export.
The textile industry is one of Bangladesh's most important, accounting for more than $5 billion in exports annually - two-thirds of the country's total exports.