Up to 150 people have been reported to have been killed and 76 wounded, with many suffering serious burns following the blast, although the number keeps rising.
Local villagers were caught in the inferno after they ran towards the overturned tanker with jerry cans to take the leaking fuel, said Mr Naseer.
Police tried to cordon off the area but were overwhelmed by scores of villagers who pushed through to reach the truck.
The tanker flipped over on a national highway about 60 miles south west of Multan. It was driving from the southern port city of Karachi to Lahore, the Punjab provincial capital, when the driver lost control and crashed.
Witnesses said about 30 motorcycles that had carried villagers to the accident site lay in charred ruins nearby. Eight other vehicles were destroyed, they added.
Many of the bodies were burned beyond recognition, said Mr Naseer.
Dr Naseer also warned the death toll was likely to rise.
The incident comes soon after more than 85 people were killed in three attacks across Pakistan, including a double suicide bomb blast in a crowded market place.
Article Appeared @http://www.itv.com/news/2017-06-25/at-least-100-dead-after-oil-tanker-overturns-on-pakistan-highway/