The incident happened late on Saturday in the province of Parwan, north of Kabul, leaving travellers on both sides of the mountainous pass stranded.

At least 12 people were killed and 37 others were injured in the incident, said Hamidullah Misbah, spokesman for the Ministry of Public Works, adding the toll was expected to rise.

“An oil tanker overturned and caught fire in the Salang tunnel, which then set several other vehicles on fire,” Misbah told AFP.

Abdullah Afghan Mal, a senior health official in Parwan, said many of the dead included women and children who were badly burned.

“Among the dead it was very hard to identify who was a male and who was a female,” he said.

The pass was now closed for traffic as rescue teams in helicopters deployed at the site, officials said.

The Salang pass, one of the highest mountain highways in the world at around 3,650 metres (12,000 feet) was built by Soviet-era specialists in the 50s and includes a 2.6-kilometre tunnel.

The pass runs through the Hindu Kush mountain range that connects capital Kabul to the north.

Hailed as an engineering feat upon completion, the Salang pass is often shut for days because of accidents, heavy snowfalls and avalanches during the winter.

In 2010, avalanches killed more than 150 people in the Salang pass.