Outside a morgue in Egypt's capital, a woman mediates between her parents. Her mother cannot believe the decomposing body before them is their son. Her father insists that it is.

"What's going on? Why hasn't anyone claimed this body," shouts one man, a surgical mask pulled below his mouth.

"The family can't decide if it's him," another man yells back.

"The father says it's his son, but the mother says it isn't."

A woman in a black dress and head scarf clutching a picture of a young man agrees to try to identify the body.

"I'm the daughter," she says, reluctant at first to see the face of the body lying wrapped in a white sheet inside a crude wooden box.

Clouds of flies hover above it, some landing on the chunks of ice placed on top of the corpse in an attempt to slow decomposition.

"Does he have a mark by his eye?" she asks the men standing around the body, in an apparent bid to avoid having to view the corpse.

Some say yes, others say no, and so the sheet is unwrapped, revealing a face dark and different, but still that of the young man in her photo.

The shocked young woman walks away, back into the crowd waiting in the filthy courtyard outside Zeinhom morgue, where dozens of bodies have overwhelmed limited capacity.

Rubbish lies in the corners, and the ground underfoot has been churned into mud.

An empty makeshift coffin leant against a wall topples over suddenly, throwing up hundreds of startled flies into the air.

Last Wednesday, nearly 600 people were killed throughout Egypt in violence that accompanied the forcible dispersal by security forces of two Cairo protest camps.

The tent cities had been set up by supporters of ousted Islamist president Mohamed Morsi, many of whom were killed as their protest camps were cleared.

On Monday, five days later, the bodies of dozens of those killed in the Rabaa al-Adawiya protest camp remain at the morgue.

When its brown metal door swings open, they can be seen inside.

But they are also outside, stacked up in two refrigerator trucks, waiting to be collected by relatives, many of whom live in provinces far from Cairo.

In the morgue's courtyard, incense sticks have been lit and strategically placed in corners in a bid to cover the smell of decay.

But when the doors to the morgue open, a wave of the smell of dead bodies overwhelms their feeble perfumed smoke.

Among the relatives are those who don't yet know if their loved ones are inside the morgue.

Others have identified bodies, but are still waiting for them to be processed.

A weeping elderly man says his friend's 15-year-old son Reda is inside.

"His father is crippled, and his mother was at Rabaa, he went to look for her and then went missing, he was shot and killed there," he cries.

Mohamed Shaaban Sayed's body is lying just inside Zeinhom's front door in an antechamber where his cousin stands watch.

"He was killed in Rabaa, and so was he," he says, pointing to the corpse next to his cousin.

Both bodies are wrapped in white sheets secured with surgical tape.

Blood has stained their shrouds and crusted on the steel stretchers below them.

Even as the morgue struggles to process the bodies it has, it receives more.

On Monday, the bodies of 37 Islamist prisoners arrive.

Authorities say they suffocated on tear gas that was fired after they took an officer hostage, but Morsi supporters say they were murdered.

Abdul Aziz Abdel Rahim, 38, is among the dead prisoners, according to his father, who is waiting outside Zeinhom.

"Some people say they suffocated, others say 'only God can know,'" he says quietly.