Emergency teams working through atrocious winter weather have rescued hundreds of people trapped in snow-bound vehicles at the world's highest mountain tunnel, the Salang Tunnel in Afghanistan.

I didn't know these were my hands. I lost all feeling. Many people haven't eaten for two days

Dr Sayed Nasir

But rescue came too late for at least four of those stranded, who perished as temperatures plunged to -40C during an ordeal that lasted more than 24 hours.

About 190 people were trapped inside the tunnel - where three of the casualties are reported to have suffocated from carbon monoxide poisoning; another 100 were trapped in 57 vehicles outside - where at least one child froze to death.

The Salang Tunnel - build by the Soviet Union 4,100 metres (13,350 feet) about sea level - was reopened to traffic only last month after being blocked for years by fighting.

Frostbite

Initial reports on Wednesday had suggested an avalanche had struck the Salang Pass, which connects north and south Afghanistan, but rescue workers at the scene said the problem appeared to have been caused by snow blown onto the road by high winds. Blizzards and the complete absence of snow-clearing equipment at the tunnel, about 100 kilometres north of the capital, Kabul, hampered the rescue effort - mounted by international teams consisting of US troops, international peacekeepers, United Nations and non-governmental organisation employees (NGOs).

Some of the rescue vehicles sent up to the pass to help clear the road soon became stuck themselves in conditions that local drivers described as the worst they could remember.

It is not known if the death toll is expected to rise - one traveller said he understood that about 20 people might have succumbed to the cold.

A reporter for the French news agency AFP at the scene said many of the children who were pulled out of cars seemed barely conscious with the cold.

"People don't have enough clothes with them and are running out of petrol," said Dr Sayed Nasir, an NGO doctor who was in one of the first cars to be released.

It was the worst weather in living memory

"The problem wasn't so much the snow as the severe wind. It was so cold one couldn't stand outside for more than two minutes," he said.

"I didn't know these were my hands. I lost all feeling. Many people haven't eaten for two days."

About 60 people were reportedly being treated at a field clinic set up halfway between Kabul and the tunnel, most of whom were suffering from frostbite and dehydration.

Recently reopened

The Salang Tunnel had been blown up by the late Northern Alliance commander, Ahmed Shah Masood, to stop advancing Taleban troops.

In 1993, dozens of people were killed in an avalanche on the same road.

The recent heavy snowfall has raised hopes that a crippling three-year drought may be broken.

But it has made many of the roads around the mountainous country impassable, blocking supplies to hunger-stricken areas.

Vehicles piled with grain are stranded in western Afghanistan, where tens of thousands of Afghans face starvation and where aid organisations have been struggling against appalling conditions all winter.