Former senator Hidayatullah was campaigning in the run-up to an election in tribal district along the Afghan border when his vehicle was hit by a remote controlled bomb, said police official Bakht Munir.

It was an improvised explosive device, said another government official, Anwarul Haq.

The Pakistani Taliban, or Tehreek-e-Taliban Pakistan (TTP), which is an umbrella group of sectarian militants, denied involvement.

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Bajur is one of several tribal districts on the border with Afghanistan, a lawless region which has long been a safe haven for Islamist militants who operate on both sides of the border.

Prime Minister Shehbaz Sharif condemned the attack, said a statement from his office, as reported by Reuters.