Hospitals treating the survivors of last week's explosion in North Korea have no modern medical equipment of any kind, according to aid workers.
Officials say many of the victims have horrific injuries
Officials from the World Food Programme described conditions as "very basic", saying that even simple items like intravenous drips were scarce.
The UN agency issued an urgent appeal for food aid for North Korea.
More than 160 people died and 1,300 were injured in the blast, which tore through Ryongchon on Thursday.
A WFP official, Tony Banbury, visited the site of the accident and spoke of the appalling suffering of those wounded in the explosion.
"The care that the patients had received when we saw
them on Sunday was very rudimentary," he said.
Many of the injured - now being treated at hospital in Sinuiju - had been facing in the direction of the explosion and had suffered facial blast wounds, he said.
"All kinds of glass, debris, dirt and pebbles had been blown
into their faces at a high velocity," he told a press conference in Beijing.
He also said he saw patients whose "skin was charred and ripped off" and others whose faces had been blackened by apparent
He said that many victims had been given sutures, but the thread was very thick and far apart.
"There seemed to be very little additional care that had been given other than bandages and
ointment," he said.
The UN team also walked around the blast site to assess the damage. Nearly 2,000 homes are said to have been destroyed in the explosion.
"There was clearly extensive devastation in the town, many homes absolutely destroyed, a school ruined," Mr Banbury said.
"We saw a number of families searching for their
belongings - what was left of them - and then loading what
little they could find onto hand-pushed carts or ox carts," he said.
"It was a very sad and poignant sight."
Many countries have now promised aid to the victims
The BBC's correspondent in Beijing, Louisa Lim, said North Korea had admitted it needed help by making a rare appeal for international aid.
The World Food Programme launched its appeal for 1,000 tonnes of food aid on Tuesday, saying aid workers had been forced to use supplies needed in other areas of North Korea to help the blast victims.
UN official Masood Hyder stressed that more than a quarter of the 23 million people in North Korea remained dependent on food aid.
"While we are all focusing on this accident, we should not
forget the larger context," he said. "The WFP is supporting
6.5 million people who do not have enough to eat."
The Red Cross launched an emergency appeal on Monday, to
raise $1.21m to buy food, clothing and cooking fuel.
"Thousands of people have lost most or all of what they had
and they were already struggling," said Niels Juel, regional relief
co-ordinator for the International Federation of Red Cross and
Red Crescent Societies.
Japan, Russia, Australia, South Korea and the United States are among the countries that have already offered to send supplies.
Neighbouring China dispatched truckloads of tents, blankets and food across its border over the weekend.
But international relief efforts have been hit by North Korea's refusal to allow South Korean aid supplies to cross the heavily guarded land border.
South Korean aid is now likely to reach North Korea by boat, but it will take up to two days by sea as opposed to four hours by land, the Red Cross said.
North Korea is notoriously sensitive about the area around the demilitarised zone (DMZ) which separates the two Koreas, and negotiating any changes to procedures there is rarely swift.
CORRECTION: A photograph that appeared in some versions of our story N Korea train blast 'kills many', published on Friday 23 April, was published in error. We said the photograph was an image of smoke from fires burning at the site of the North Korean accident at Ryongchon station. It was not, and we apologise for the mistake.