A bomb hit a police van protecting a polio vaccination team in northwest Pakistan on Monday, killing two people and wounding 12 others, police said.
The attack took place on the third and last day of a UN-backed vaccination campaign in a suburb of the city of Peshawar, police said, adding that a policeman was among the two dead.
Pakistan is one of only three countries in the world where polio is still endemic, but efforts to stamp out the crippling disease have been hit by repeated attacks on health teams.
Militant groups in the restive country have rejected vaccination as a Western plot against Muslims and banned teams from giving out polio drops in some areas.
"It was an IED blast and the target was policemen," Najeebur Rehman, a senior police official told AFP, adding that the bomb went off just as officers reached the village to provide security to polio teams.
Nasir Durrani, police chief for northwestern Khyber Pakhtunkhwa province, of which Peshawar is the capital confirmed the incident and death toll.
"Most of those wounded were policemen," Durrani said.
Raheel Shah, another police official told AFP that polio workers remained safe in the attack as they were inside a health clinic in the village.
Authorities said bomb disposal experts defused a second device close to the site of the first blast and had halted polio vaccination in Badaber village, where the incident took place.
"A second bomb weighing five kilo-grams of explosive has been defused. We have suspended the campaign for time being," Zahurul Islam, a senior government official in Peshawar told AFP.
Islam said all those wounded in the blast were policemen, adding that a total of 54 polio workers including 24 women were present inside the clinic.