The explosion killed at least 74 people and injured several others near the town of Rahim Yar Khan in the south of Punjab province.
A Pakistani government official says the death toll from a massive fire on a train that was travelling in eastern Punjab province has jumped to at least 74.
Jamil Ahmed, a deputy commissioner in the town of Rahim Yar Khan, says the fire on Thursday was caused by a cooking gas stove.
He says dozens of passengers were also injured in the accident near the town of Liaquatput in Punjab province.
More than a dozen people are in critical condition meaning the death toll could rise.
Railways Minister Sheikh Rashid Ahmad said the fire took place Thursday when some of the passengers were preparing breakfast on the speeding train in violation of rules.
The fire destroyed three of the train's carriages.
"Two cooking stoves blew up. They were cooking, they had (cooking) oil which added fuel to fire," Minister for Railways Sheikh Rashid Ahmed told Geo television.
"Most deaths occurred from people jumping off the train," he added.
People sneaking stoves onto trains in order to prepare meals on long journeys is a common problem, the minister said.
Pakistan’s colonial-era railway network has fallen into disrepair in recent decades due to chronic under-investment and poor maintenance.
Eleven people were killed in an accident in July and four in another one in September.
About 130 people were killed in 2005 when a train rammed into another at a station in Sindh province, and a third train hit the wreckage.
TRT World's Ali Mustafa has more.