At least 30 people were killed when a passenger bus slammed into a speeding oil tanker early Sunday near the Pakistani port city of Karachi, police said.

"The bus carrying some 50 passengers hit the over speeding oil tanker,which accordingto initial reports was coming in a wrong direction," senior police official Rao Muhammad Anwaar told AFP.

"The bus caught fire after the accident, killing at least 30 people."

The bus was en route to the town of Shikarpur from the southern port city of Karachi when the collision occurred.

The victims included women and children, some of whom were charred beyond recognition, Anwaar added.

A few passengers escaped unhurt after they jumped out of the bus windows, another police official Muhammad Jan said, confirming the toll.

"We are trying to ascertain if the driver of the oil tanker was solely at fault or whether the bus driver also showed negligence," Anwaar said.

Pakistan has an appalling record of fatal traffic accidents due to poor roads, badly-maintained vehicles and reckless driving.