LAHORE: The death toll from the collapse of a Pakistani factory has reached 44, rescue officials said on Sunday, nearly five days after one of the country's deadliest industrial accidents in recent years.

More than 100 injured survivors were pulled from the rubble after the factory collapsed on Wednesday night, but no one had been recovered alive since Friday night, said Dr Zulfiqar Ahmad, the executive district officer health Lahore.

"Now we are using sniffer dogs to try to find people," Ahmad said. "Only the ground floor is left ... It will take another day to clear all the rubble, after which we will be in a better position to tell the final death toll."

"Today ... the whole operation was stopped for 45 minutes and a pin drop silence was maintained to hear sounds through voice sensors. But we found nothing."

A handful of devastated family members still clustered around the site, clutching photographs and desperately ringing phones whose lines had gone dead.

"We are here for the last three days. Every moment gives us hope that my younger brother Rizwan will come out of rubble alive," said Muhammad Imran, whose 16-year-old brother Muhammad Rizwan worked at the factory.

He spoke to his brother ten minutes before the collapse, he said, and had been calling since then. On Saturday, Rizwan's phone went dead.

There were 160 to 175 factory workers and more construction workers inside the building when it collapsed, said Kamran Ali, a factory official at the site.

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 large cracks appeared in the building following last month's 7.5 magnitude earthquake.

The owner was among those killed in the collapse of the factory, which manufactured plastic bags 20 km (12 miles) south of the eastern city of Lahore.

The accident will once again raise questions over Pakistan's lax enforcement of safety and building codes.

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