“The police van that came under attack was taking personnel for the protection of polio staff,” Rahmat Ullah, a senior police officer, told AFP.

He added that “there is a girls’ school near the place of the attack” in the city of Mastung in Balochistan province.

Pakistan and neighbouring Afghanistan are the only countries where polio remains endemic and vaccination teams are frequently targeted by militants waging a campaign against security forces.

“Seven individuals: one police officer, five children and one shopkeeper” were killed in the attack at the city’s main market, senior officer Abdul Fatah told AFP.

Interior minister Mohsin Naqvi earlier put the death toll at three children and one police officer.

“Targeting children is an act of brutality,” he said in a statement.