LAHORE, Pakistan (AFP) - At least 24 worshippers were killed when the roof of a mosque collapsed in the eastern Pakistani city of Lahore and an unknown number are still buried under rubble, officials said.

The accident on Tuesday happened in Daroghawala, a low-income neighbourhood in the outer city with narrow and congested streets that hampered rescue efforts. Recent monsoon rains that have caused deadly flooding in Pakistan's Kashmir region and Punjab province may have contributed to the collapse, Punjab food minister Bilal Yasin told AFP.

Officials said that there were up to 30 people at the daily afternoon prayers.

The roads nearby are busy, preventing heavy machines from entering the area to remove the debris. Residents are helping the rescue effort, with television footage showing them making a line to remove debris by passing it hand-to-hand.

Zahid Bahsir, 35, who was being treated in hospital for injuries to his head and shoulders, said all he remembered was the recital of the prayer - and then a loud noise, dust and debris.

"It was just another normal day when I stood with others to say my prayers, but suddenly everything turned into pain, dust and it was suffocating," Bashir told AFP. "I am lucky to have survived this. Life and death is in the hands of Allah."

Bashir said the prayer leader had also survived. About 30 locals regularly worship at the mosque, he added.

Floods across India and Pakistan due to the monsoon rains have stranded hundreds of thousands of people and killed 400. Many of the more than 200 killed in Pakistan so far have been victims of collapsed roofs.

Safety standards, particularly in construction, are very lax in nuclear-armed but impoverished Pakistan. At least 21 people including including 16 women and four children died when a factory collapsed in Lahore in 2012. The collapse of the Margalla Towers apartment block in Islamabad in a 2005 earthquake killed 78 people, with shoddy construction blamed.