A bomb killed at least one policeman and wounded another during a vaccination campaign for polio and other diseases among children in Pakistan's troubled northwest on Sunday, officials said.
The incident happened in Budhni area on the outskirts of Peshawar, the gateway to the country's restive tribal regions, where the military has been battling Taliban and Al-Qaeda-linked militants.
"The police team was being deployed in Budhni area before the start of the campaign when a remote controlled bomb exploded near their van, killing one police official and wounding another one," local senior administration official Zaheer-ul-Islam told AFP.
A senior local police official, Faisal Mukhtar, confirmed the incident and casualties.
Militant groups see vaccination campaigns as a cover for espionage, and there are also long-running rumours about polio drops causing infertility.
More than 40 people including health workers and police officials providing security to the teams administering polio drops to children have been killed in Pakistan in different incidents of violence since December 2012.
The latest campaign, which started early this month, will continue until April. It sees vaccinators go door-to-door every Sunday across Peshawar to administer drops to children for various diseases including polio, tuberculosis, tetanus, whooping cough, measles and hepatitis.
Pakistan is one of only three countries in the world where polio is still endemic, along with Afghanistan and Nigeria.
According to the World Health Organisation, Pakistan recorded 91 cases of polio last year, up from 58 in 2012.
The World Health Organisation has warned that the Pakistani city of Peshawar was the world's "largest reservoir" of polio.
Pakistan's failure to defeat polio stands in stark contrast to its neighbour and great rival India, which recently celebrated the eradication of polio three years after its last case.