The attack happened on the road towards the garrison city of Kohat near the lawless tribal belt, a stronghold of militants blamed for violence plaguing both Pakistan and neighbouring Afghanistan.

“The death toll in the car bomb blast has now risen to 13 while more than 35 have been wounded,” city police chief Imtiaz Altaf told AFP.

A senior doctor in the local Lady Reading hospital, Rahim Jan confirmed the new toll, adding that seven injured people were in a critical condition.

Several of the bodies were charred beyond recognition, he said.

Around a dozen passenger coaches were heavily damaged, with pieces of human flesh scattered and blood smeared on the ground.

At the main hospital in Peshawar an AFP reporter said the wounded cried and relatives of the dead sobbed over the bodies of their loved ones.

Dilawar Khan, 60, who was wounded in his left shoulder, told AFP his 12-year-old son Abdullah was killed while helping him run a tea stall at the bus station while on a break from school.

“I was preparing tea for the drivers and my son was serving tea for some other drivers when the huge blast happened,” Khan said, through his tears.

“Something like shrapnel hit me in the shoulder but I was conscious. Then I was brought to hospital and saw my son’s dead body. I’ve lost everything.” There was no claim of responsibility and the precise target was unclear, but attacks blamed on Taliban and other homegrown extremists opposed to the government’s support for the US war in Afghanistan are common.

“At the moment I can’t say what the exact target of the bomb attack was but all those killed were innocent civilians,” Mohammad Siraj, the top government official in Peshawar, told reporters.

Tahir Ayub, a senior police official, told reporters that most of those killed were passengers waiting to board coaches.

“Two children were among the dead. According to a preliminary investigation, the bomb was planted in the car,” he said.

“The bomb was planted in a car at the station, and around 40 kilogrammes of explosives were used,” police official Shafqat Malik told reporters.