The buses were stopped at a police station on the main road between Bam and Zahedan in the country’s south when the truck smashed into them. The road is along a major drug smuggling route that runs from Afghanistan through Iran and on to the West, and buses often stop at police stations on highways to be inspected for contraband.

It is thought that many casualties could have been prevented but the isolated position of the check point meant there wasn’t sufficient firefighting equipment nearby to douse the flames.

State television reported that the flames engulfed six buses and five other trucks, two of which were carrying tar, fuelling the massive inferno.