At least 20 people were burnt alive in a collision between a passenger bus and an oil tanker in the Punjab province of Pakistan on Tuesday.

The accident occurred on a motorway in Multan, some 350kms from Lahore reportedly because of overspeeding.

Traffic remained suspended on the motorway for several hours after the accident.

"Twenty people have perished in a collision between a bus which was going to Karachi from Lahore and an oil tanker. After the collision, both the bus and tanker caught fire and the passengers were burnt alive," a Rescue 1122 spokesperson added that six passengers who suffered burn injuries were shifted to Nishtar Hospital in Multan where their condition is stated to be critical.

"Most bodies of the perished passengers are burnt completely and beyond recognition. These bodies will be handed over to the families after a DNA test," he said.

He further said after the accident the fire engulfed both vehicles and the rescue operation was very difficult for the rescue and firefighter teams.

Punjab Chief Minister Parvez Elahi has expressed grief over the loss of precious lives in the accident and directed the health authorities concerned to provide better treatment to the injured. He also directed the administration to cooperate with the families of the deceased to identify them.

On Saturday, at least 13 people were killed after a loaded truck collided with a passenger bus in Pakistan's Punjab province.

Road accidents have become all too frequent in Pakistan, pointing to the fact that shoddy infrastructure, dilapidated vehicles and lack of compliance with traffic rules add to the overall situation.