Gunmen shot and killed a policeman deployed on security detail for polio vaccinators in north-western Pakistan on Tuesday, in yet another attack on health workers.
The country struggled to contain the spread of the crippling disease.
Another policeman was wounded in the attack that took place in Orakzai district of the province of Khyber Pakhtunkhwa bordering Afghanistan, a local police officer said.
Police said that at least three militants behind the attack were chased and killed by the security forces.
The latest attack came on the second day of a nationwide vaccination campaign targeting 45 million children under the age of 5.
The country, which had only six cases last year, has so far reported 41 new cases of polio.
Officials say that tens of thousands of children missed out on vaccines amid a recent surge in violence, contributing to the spike in new cases this year.
Militants linked with al-Qaeda often attack health workers.
Dozens of vaccine handlers and security officials have been killed by Taliban militants in the past.
The militants accuse the health workers of acting as spies and claim the polio vaccine is intended to make Muslim children sterile.
Pakistan and neighbouring Afghanistan were among the few countries in the world where new polio cases still surfaced. (dpa/NAN)