Two vehicles were destroyed, but the polio workers survived the attacks, officials said.

Two bombs went off Saturday in Pakistan’s north-western tribal region, killing 10 and injuring 11 policemen who were guarding polio vaccinators, officials said.

The men from the tribal Khasardar Force were escorting a team of polio vaccinators in the area of Jamrud in Khyber district when two vehicles were targeted with separate bombs planted by the road, an official from the tribal administration said.

He said the polio workers survived the attacks and that the two vehicles were destroyed.

Private Geo TV reported that a child was also killed.

No group has yet claimed responsibility for the bombings, but Islamist militants have targeted vaccination teams in the past.

In the last year alone, officials say that about two dozen health workers and security officials deployed to protect them have been killed by rebels.

Polio has reappeared in parts of north-western Pakistan under the control of Islamist militants linked to al-Qaeda, according to the World Health Organization (WHO).

Insurgents accuse health workers of acting as spies for the United States, and claim the polio vaccine is intended to make Muslim children sterile.

Following widespread vaccination campaigns since the 1950s, polio is only endemic in Pakistan, Afghanistan and Nigeria.

WHO says Pakistan is the only country in the world where the number of new polio cases was on the rise in 2013.