Blast targeted a passenger van in the Lower Dir district near the village of Bunr, said Hussain Ahmed, the official.

Should the U.S. launch a strike, Jafari suggested that Iran could respond with missile salvos at U.S. bases in the Gulf.

The Pope's visit has also coincided with anti-US protests across the region over a film deemed insulting to Islam.

At least one Afghan police officer turned his gun on NATO troops at a remote checkpoint in southern Afghanistan.