The incident occurred in the Damadola area of Bajaur Agency. Political authorities said Nawab Khan, levy troop, was on duty with polio vaccination team in Damadola area of Mamond tehsil when unknown armed men attacked the team with automatic weapons.
Khan died on spot while the gunmen managed to flee the scene, the official said, adding investigations into the case is going on.
Pakistan is one of three countries where polio is still categorised as an endemic viral infection. The other two countries are Afghanistan and Nigeria.
The last attack on polio workers came in March when the body of an anti-polio woman health worker who was kidnapped by some armed men from Peshawar.
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The health worker was found dead with torture marks on her body.
Earlier in March, 12 paramilitary troops and a child were killed in two blasts targeting a polio vaccination team in northwest.
Taliban violence is the prime hurdle against immunisation of children. The militants allege the vaccine is a conspiracy by the West to sterile Muslims.