A massive fire caused by an exploding gas stove has erupted on a train travelling in Pakistan's eastern Punjab province, killing at least 65 passengers.

Flames roared through the train cars as the train approached the town of Liaquatpur in Punjab, they said, the latest tragedy to hit Pakistan's dilapidated, poorly maintained and mismanaged rail system.

Deputy Commissioner Jamil Ahmed said the death toll had risen steadily since the early morning. The fire broke out when a gas stove exploded as breakfast was being prepared on board, he added.

Several of the injured had jumped off the train - many to their deaths - after the fire broke out, Ahmed said.

Minister for Railways Sheikh Rashid Ahmed told Geo television the confirmed death toll was at least 65.

"Two stoves blew up when people were cooking breakfast, the presence of kerosene with the passengers in (the) moving train further spread the fire," he said.

"Most deaths occurred from people jumping off the train," he added.

Television pictures showed fire and black smoke pouring from the train's windows after it came to a stop on a stretch of line flanked by fields.

"People were jumping off, some of them were on fire," a witness told Geo.

The train eventually screeched to a halt. Poor passengers often bring their own small gas stoves on the trains to cook their meals, despite rules to the contrary, according to Railways Minister Sheikh Rashid Ahmed.

Safety regulations are often ignored in the overcrowded trains.

Through the morning hours, rescue workers and inspectors sifted through the charred wreckage, looking for survivors and aiding the injured.

Local Pakistani TV footage from the scene showed a huge blaze raging as firefighters struggled to get it under control.

Authorities said they were still trying to identify the victims and that the lists of fatalities and those injured were not ready yet.

Another train has been dispatched to bring the survivors to the city of Rawalpindi, they said. Yasmin Rashid, a provincial minister in the Punjab, told reporters that the medical staff were providing the best possible treatment for the injured at a hospital in Liaquatpur.

Those critically injured will be taken ambulances to the city of Multan, the largest city nearest to the site of the accident.

The train was on its way from the southern port city of Karachi, the capital of southern Sindh province, to the garrison city of Rawalpindi when the blaze erupted, said Ahmed, the deputy commissioner.

Pakistan's military said troops were also participating in the rescue operation.

President Arif Alvi and Prime Minister Imran Khan issued statements expressing grief over the tragedy.

Train accidents in Pakistan are often the result of poor railway infrastructure and official negligence.

Media reports have suggested that railways officials did not notice when passengers boarded the train, carrying individual gas stoves.

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 accident 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.