Pakistani health officials say a bomb has killed two polio-vaccination workers in the troubled northwestern Kurram tribal region.
Antipolio campaign manager Jawad Ali said the two men were visiting Mali Khel village on January 31 when a remote-control explosive device planted alongside the road went off, killing them on the spot.
No group has claimed responsibility for the attack.
Taliban militants have opposed the antipolio campaign, condemning it as a cover for espionage.
At least 11 polio workers have been killed across Pakistan in attacks since December.
Pakistan, along with Afghanistan and Nigeria, are the only countries in the world where polio remains endemic.
Based on reporting by AFP and dpa