A bomb that exploded near a polio vaccination team in the volatile northwestern Pakistani city of Peshawar on Monday killed at least two people, and possibly as many as six, police said, the latest in a string of attacks against health workers.
Islamist violence has been on the rise in Pakistan, undermining Prime Minister Nawaz Sharif's efforts to tame the insurgency by opening peace talks with the Taliban.
Peshawar has borne the brunt of much of that violence, with the frontier city near the Afghan border hit by at least four attacks that killed scores in the past month.
Monday's blast appeared to target police who were assigned to protect the vaccination team. Health workers have been attacked repeatedly since the Taliban denounced vaccination as a Western plot to sterilize Muslims.
Two people were killed and around 20 people wounded, said Peshawar police official Najeeb ur-Rehman. Other police reports suggested up to six people were killed.
The bomb was placed directly outside a clinic in Sulemankhen, on the outskirts of the provincial capital of Peshawar, Rehman said.
Gunmen killed two female polio health workers in the same area earlier this year. Similar attacks have been staged elsewhere in Pakistan and also in Nigeria, where Islamist gunmen killed nine health workers in February.
Such attacks hamper efforts by global health organisations to eradicate polio, a virus that can cause irreversible paralysis within hours of infection. Polio remains endemic in only three countries: Pakistan, Afghanistan and Nigeria.
A small but vocal minority of religious leaders in those countries accuse the West of using the vaccination campaign to cover up a variety of anti-Islam plots.
Eight new cases of polio were reported in Pakistan last week, according to the Global Eradication Initiative.
Violence in Pakistan's often lawless northwest has shown few signs of abating despite efforts to open talks with separate Taliban groups in Pakistan and neighbouring Afghanistan.
A car bomb killed 42 people in an ancient market in Peshawar on Sept. 29, a week after an attack by a Taliban faction on Peshawar's Anglican church killed about 80 people. (Writing by Katharine Houreld; Editing by Paul Tait)