Nepalese doctors set up makeshift operating theatres in a hospital car park Sunday as they worked round the clock to treat the wounded from a monster quake that has also left morgues overflowing with bodies.

As disaster officials said nearly 6,000 people were injured in Saturday's 7.8 magnitude quake, medics in the impoverished Himalayan nation told how they had been unable to save some of the most grievously wounded.

Their efforts were being further hampered by fresh aftershocks that were felt throughout much of the morning, making many patients too scared to stay inside medical facilities.

Samir Acharya, a doctor at Annapurna Neurological Hospital, described how medics were working out of a tent set up in a parking lot after being overwhelmed by patients.

Even if there was room, some were too scared to stay in the building, said Acharaya who together with his colleagues has been flat out ever since the earthquake struck on Saturday lunchtime.

"We have treated many people since yesterday, the majority children," said Acharya.

"Most patients have head injuries or fractures. Two of our patients died, two are critical," he said, as people wept outside the hospital while they waited for news of loved ones inside.

With the death toll from the disaster rising above 2,200, hospitals were also struggling to find places to store the bodies.

At the city's oldest Bir Hospital, there were around a dozen dead bodies placed on the floor with relatives trying to swat away the flies.

A security guard said that around 100 bodies had been taken away for cremation since Sunday morning.

"In some cases, there was a delay as the relatives or immediate family members were also injured in the quake or couldn't reach the city," he said.

Oxfam Australia chief executive Helen Szoke said the nation's creaking infrastructure was struggling to cope with the scale of the disaster.

"Electricity has been cut off, communication systems are congested and hospital are crowded and are running out of room for storing dead bodies," she told AFP.

- Foreign volunteers -

At the national trauma centre in Kathmandu, senior surgeon Santosh Poudil told AFP that his team had not slept since the disaster struck, as they tended to at least 1,000 victims with a variety of injuries.

"Almost 25 percent of these patients that I saw had serious trauma injuries -- on the back, legs, arms and head, often at the same time," he told AFP.

"We are prioritising which patients need immediate attention for surgery and other procedures."

Medics were being helped by an army of volunteers, including foreign tourists who were in the Himalayan nation when the disaster struck.

Heli Camarinha, a 28-year-old Portuguese tourist, responded to a plea for help on local television.

"I was really lucky to have not been injured during the earthquake yesterday. Today morning when I saw the local news that hospitals etc need volunteers I decided to come here to try and help," Heli told AFP.

"I have a first aid certificate and some experience in social work back home. I have been doing whatever I can, from cleaning the patient wards, helping transfer them to different hospital floors on the stretcher, basically any way possible."

One of those being treated at the trauma centre was 25-year-old Suresh Pariyar who suffered back injuries when a building he was walking past in the capital suddenly pancaked.

"I had gone to collect money from a friend in the market. A house collapsed within seconds after the earthquake struck and a cloud of dust enveloped the entire area," Pariyar told AFP.

"The earth was shaking and moments later I found myself under the debris in pain and pleading for help."

"I was begging for help but everyone was running in panic to save themselves. I crawled from under the debris. My friend's 13-year-old son died instantaneously just meters away from me."

"A police van picked me up and brought me to hospital."

Rickshaw driver Dibesh Gautam said he had been ferrying victims to various hospitals from first light.

"I must have brought over 35 people to the hospital yesterday," Gautam told AFP.

"I have been working since 5:30 in the morning. I am scared too, but we have to do what we can to help others."

Santosh Sharma, the international medical charity CARE's emergency response coordinator in Kathmandu said there was an urgent need for more supplies.

"More than 40,000 people are getting treatment in hospital, but there is no room inside the hospitals. Many are getting treated in the compound of the hospital," said Sharma.

"All of the particularly vulnerable -- children, breastfeeding mothers, people with chronic diseases -- they have been suffering a lot. It's essential to get help to these people as quickly as we can."