Rescuers at the site of a collapsed factory in Pakistan continued to dig through the rubble yesterday, as the death toll rose from 18 to at least 21, officials said, describing the latest tragedy to spotlight poor safety standards in South Asia.

Rescue officials said 102 survivors had so far been pulled from the wreckage of the factory, which manufactured polythene shopping bags, 20 kilometres south of the eastern city of Lahore, and collapsed on Wednesday night.

Bodies were recovered by rescue crews using heavy construction machinery and other tools to dig through the debris, said Mohammad Younis Bhatti, a rescue official, yesterday.

Earlier, officials estimated 150 people had been in the building when it collapsed. Rescuers had to move slowly, government officials said, to avoid further injuries to those still trapped.

I ran towards the stairs but they collapsed before I reached there and then the whole building collapsed

Injured survivors said the factory’s owner, who was adding a new floor to the building, had ignored advice from his contractor and pleas from his workers to stop construction after cracks in the walls appeared following a powerful earthquake last week.

The quake of magnitude 7.5 killed more than 300 people in Pakistan and the northern parts of neighbouring Afghanistan and damaged thousands of buildings.

Muhammad Ramzan, 22, one of the survivors, said that he had witnessed cracks first appearing in the structure, moments before the collapse.

“Suddenly, I saw cracks appearing in the pillars. I immediately drew the owner’s attention towards the cracks. He was watching them when the roof collapsed and I saw him being crushed by a heap of concrete that led to his death,” he said.

Rescue workers carry an injured man who was dug out from the rubble after a factory collapsed near the eastern city of Lahore, Pakistan, yesterday.

Many survivors were able to guide rescuers by calling relatives on their mobile phones.

“I ran towards the stairs but they collapsed before I reached there and then the whole building collapsed. I stayed in touch with my father on the phone and was recovered after 13 hours,” said Mohammad Asghar, 16, who suffered a broken arm and head injury.

Pakistan’s construction sector is plagued by poor oversight and developers frequently flout building codes.

In September 2012, 289 people burned to death in a fire at a garment factory in Karachi. On the same day, a fire at a shoe factory in Lahore killed 25.