Police say at least one person has died and more than 50 have been injured in the incident in the Tauern tunnel, south-east of Salzburg.

The fire destroyed 23 cars and lorries, and officials say there may be up to three more bodies among the wreckage.

Choking smoke and fierce heat initially forced back rescuers - seven firefighters were among those taken to hospital.

Witnesses said the blaze was caused by a collision between a car and a lorry carrying paint, about 600 metres (2,000 ft) into the northern entrance of the Tauern tunnel.

The blaze comes just two months after a fire in the Mont Blanc tunnel, under the Alps on the French-Italian border, which claimed more than 40 lives.

Like the Mont Blanc tunnel, the Tauern does not have an escape tunnel parallel to the road system - a design criticised in the initial investigation into the Mont Blanc blaze.

Series of blasts

Temperatures inside the tunnel soared to 1,000 C

The Tauern crash was followed by a series of explosions which spread the fire to other vehicles.

The tunnel, south-east of Salzburg, then filled with heavy smoke, hampering the rescue effort and causing confusion both inside and outside the tunnel.

Up to 60 vehicles were involved in the accident, although many of the passengers were able to make their way to safety on foot.

Officials said they were unable to tell whether anyone remained trapped inside because of difficulties gaining access to the tunnel.

There are fears that the death toll could rise.

Communications broken

The BBC's Nigel Glass: "Rescue attempts have been terribly hampered"

There are unconfirmed reports that sections of the tunnel wall in the immediate vicinity of the accident had collapsed due to the intense heat.

"Emergency telephone lines have broken down completely, the wires probably having melted in the heat," said a spokesman for the fire brigade.

Officials said that the temperature inside the tunnel had peaked at around reached 1,000C (about 1,800F).

Eyewitness Franz Fritzl told reporters: "I heard screams: 'I am alight. Help us, help us'."

State radio reported that rescuers approaching from the southern entrance had difficulty reaching people, some of whom were trapped in their cars.

One emergency worker said: "We don't know if anyone is still inside, but if so, we probably won't be able to save them."

The 6.4km (4 mile)Tauern tunnel is on one of the main motorways linking southern and northern Austria, and the accident has caused queues several kilometers long at both entrances to the tunnel.

Mont Blanc horror

The crash has prompted immediate calls in Austria for parallel escape routes to be built at the 25-year-old Tauern and the nearby Katschberg tunnel.

Some more expensive tunnels have separate tubes for traffic going in opposite directions and a third, smaller tube for escapes.

A report into the Mont Blanc inferno says the lack of parellel escape routes may have contributed to the disastrous consequences of the initial fire.