The accident happened close to the Chinese border

In the first independent account, the Red Cross said the train blast killed at least 54 people and injured 1,200.

But diplomatic sources in Pyongyang say the figure is much higher, as reports indicate the blast happened when two wagons of dynamite hit a live wire.

North Korea has made no official statement on the blast at Ryongchon, 20km from China's border.

Shelter needed

A Red Cross team sent to the scene has reported that 1,850 homes have been flattened and 6,350 seriously damaged.

"It is a scene of great destruction," John Sparrow, a spokesman for the International Red Cross in Beijing told the BBC.

Mr Sparrow, who is in contact with the North Korean team, said the number killed was almost certain to rise.

The Red Cross is working to get shelter and medical supplies to the area where many people are now braving their second night out in the open.

South Korean media reports initially talked of up to 3,000 people dead or wounded.

N Korea: Secret state Mystery surrounds blast

An Irish aid worker in Pyongyang says North Korean officials told her that 150 people, including some schoolchildren, had died.

Anne O'Mahony, regional director of Concern, also said foreign officials had been invited by the North Korean authorities to visit the scene on Saturday.

Diplomatic sources in Pyongyang say the casualty figures are in the thousands.

The blast was initially thought to have been caused by two trains colliding. But North Korean government sources have been quoted as saying it was triggered when two train carriages carrying dynamite came into contact with a live power cable.

Border open

State television in North Korea has not reported the disaster, concentrating instead on the visit by the country's leader, Kim Jong-il, to China.

WORLD'S WORST TRAIN DISASTERS April 2004: Ryongchon, N Korea - 54 confirmed dead; many more casualties feared in station explosion February 2004: Neyshabur, Iran - at least 300 killed when a runaway train explodes June 2002: Dodoma region, Tanzania - at least 200 killed when passenger train collides with goods train Feb 2002: Egypt - 300 killed in fire on train travelling to Cairo June 1989: Ufa, Russia - More than 400 killed in gas explosion under two trains Aug 1995: Uttar Pradesh, India - 300 killed in train collision June 1981: Bihar, India - 800 killed when cyclone blows train into river World's worst rail disasters

Western embassies in the North Korean capital, contacted by BBC News Online, said people in Pyongyang had absolutely no information about the incident, and were shocked when they heard the news.

Despite the official silence, North Korea has responded to their offers of assistance, aid agencies say.

The BBC's Francis Markus says that is seen as a welcome development given Pyongyang's longstanding obsession with self-reliance.

South Korea, Australia, Russia and the UK are among several countries to have offered help.

People living across the border in the Chinese town of Dandong have been getting news of the situation in Ryongchon and some have gone into North Korea to try to help family members, the French news agency AFP reports.

"As soon as the explosion happened a lot of homes collapsed. Many people are using canvas or plastic to shield themselves from the weather," Li Kaisheng, who has spoken to relatives in Ryongchon, told AFP.

Doctors in Dandong said they were preparing for a major emergency but have so far seen no victims.

'Bombardment'

The accident happened at about 1300 local time (0400 GMT) on Thursday, South Korea's official Yonhap news agency said.

"The station was destroyed as if hit by a bombardment, and debris flew high into the sky," Yonhap quoted its sources as saying.

Ryongchon has a population of 130,000, and is a manufacturing and transport centre.

The incident is reported to have happened nine hours after Kim Jong-il passed through on his way home from a visit to Beijing.

He had been in China to discuss North Korea's nuclear programme.

South Korean officials say it appears to have been an accident and not linked to Mr Kim's trip.