Hospitals on Monday struggled to treat scores of severely burned victims of a fuel tanker explosion that killed close to 160 people in Bahawalpur, as Prime Minister Nawaz Sharif flew back from an overseas trip to visit the injured.

Dr Nahid Ahmed at the Nishter Hospital in Multan said the death toll has steadily been rising and reached 157 on Monday. He said 50 more severely burned victims were being treated at his hospital.

More than 118 people were injured in the explosion, which came as people gathered to collect leaking fuel after the tanker overturned on Sunday, government officials and rescue workers said.

The disaster was one of several deadly events to mar the run-up to the Eidul Fitr holiday. Close to 100 people were killed in bombings in Quetta and Parachinar on Friday, which were claimed by the Jamaatul Ahrar and Lashkar-e-Jhangvi Al Alimi, respectively.

A burst tyre apparently caused the speeding fuel tanker to overturn on a sharp bend on a highway on the outskirts of the city of Bahawalpur, provincial spokesman Malik Muhammed Ahmed Khan said.

It was not clear what triggered the fireball, but on Sunday, a spokesman for rescue services said someone was believed to have lit a cigarette.

“Rehabilitation and treatment of the victims is our top priority,” Khan said.

Hospitals are also arranging DNA testing to identify the many bodies that were charred beyond recognition. At least 20 children are among the dead.

Many of the burn victims have been moved to Karachi and Lahore. Governments hospital are often-underequipped, and the ones in Bahawalpur and nearby Multan were set up only to handle small numbers, Khan said.

The oil tanker driver, who survived, has been detained to assist in an investigation, but early reports do not indicate human error, Khan said.

He said a separate investigation was underway to see why police did not disperse the crowds of people who gathered to collect fuel.

“Police did try but we are looking into what went wrong,” he said.

Prime Minister Sharif visited the injured in Bahawalpur's Victoria Hospital on Sunday after flying home from a trip to London.