Doctors in Afghanistan have told the BBC that many children may have been killed in Wednesday's earthquake.
More than 1,000 people died in the disaster and heavy rain, threadbare resources and rugged terrain are hampering rescue workers.
The Taliban authorities have called for more international aid. Communication networks are also badly hit.
"We can't reach the area - networks are too weak," a Taliban spokesman was quoted by Reuters as saying.
The United Nations is among those scrambling to provide emergency shelter and food aid to remote areas in the worst-hit Paktika province.
Afghanistan's health system was facing near collapse even before the disaster.
Survivors and rescuers have told the BBC of villages completely destroyed near the epicentre of the quake, of ruined roads and mobile phone towers - and of their fears that the death toll will rise further. Some 1,500 people were also injured, officials say.
Most of the casualties so far have been in the Gayan and Barmal districts of Paktika. Locals report dozens of villages have collapsed.
"Seven in one room, five in another, four in another, then three in another, have all been killed in my family," she said from her hospital bed.
"There was a rumbling and my bed began to shake," another survivor, Shabir, told the BBC.
"The ceiling fell down. I was trapped, but I could see the sky. My shoulder was dislocated, my head was hurt but I got out. I am sure that seven or nine people from my family, who were in the same room as me, are dead."