Many parts of Cairo are densely crowded, packed with families who poured into the city from impoverished rural areas. Some districts hold about 100,000 people per square mile (41,000 per square km) and residents say they have suffered from decades of government neglect.

An Egyptian woman walks among the rubble in Manshiyet Nasser shanty town September 6, 2008. [Agencies]

The shantytown of Manshiyet Nasser, with its red brick houses and unpaved narrow alleys is famously overcrowded, with entire families sometimes squeezed into a single room.

A woman in a white veil screamed "My children, my children! I didn't get anyone out, I need to see them, even if they're dead!"

Rescue efforts were moving slowly. MENA said the authorities had sent for heavy lifting equipment, and were evacuating parts of the area because new cracks had appeared in the cliff face.

People were sifting through the rubble to recover their meagre belongings. Visible through the debris were household items; broken plates, satellite dishes, pans, blankets -- even dead chickens.

Some 30 riot police were deployed to the area and were standing on top of the rubble, a Reuters eyewitness said.

Much of the digging was being done by relatives and neighbours, tugging at piles of rocks and debris by hand in their search for survivors or bodies. Rescue workers were using pickaxes to break up large rocks.

Many residents said they had reported a small rockslide to local authorities weeks ago, but accounts differed as to the outcome of the incident.

One resident, who gave her name only as Umm Mohamed, showed a Reuters correspondent damage to her house from the recent rockslide. The walls were severely cracked and leaking, and clouds of dust rose from the walls when struck.

"If you had children, would you want them to live here? No one paid any attention to us," said Umm Mohamed.

A similar incident occurred almost 15 years ago, when a 3,000-tonne chunk of rock broke off the Moqattam plateau, an escarpment on the eastern edge of the Nile valley, and crushed houses in Manshiyet Nasser, burying at least 50 people.