As many as 60 people are feared to have burned to death on Saturday when the cylinder of a gas-run bus exploded after it skidded into a ditch with some 75 passengers on board in south-eastern Bangladesh, police said.

Eye-witnesses and police said fire engulfed the bus as it skidded into the roadside ditch near Comilla city, while trying to avoid hitting a three-wheeler autorickshaw.

"The victims died almost instantly as the fire quickly engulfed the vehicle after the gas cylinder exploded," a police official at the scene said adding, the survivors were sent to local health facilities mostly with severe burn injuries.

Police and fire brigade rescuers were still trying to recover the burnt bodies.

The apparently overcrowded bus was carrying the passengers from Dhaka to the south-eastern port city of Chittagong.