Peshawar: Unidentified gunmen shot dead a policeman escorting a team of polio workers in northwest Pakistan on Tuesday, a day after a nationwide campaign was launched against the crippling disease still endemic in the country.

Several school students in Pakistan's Khyber-Pakhtunkhwa province reportedly fell ill and were taken to hospital on Monday after being given anti-polio drops during a country-wide campaign aimed to administer anti-polio drops to 39 million children under five years of age.