Officials in Pakistan say militants have kidnapped 11 teachers involved in a polio vaccination campaign for children.
Authorities say the workers were kidnapped Saturday in the Bara district of the Khyber tribal region along the border with Afghanistan.
Militants frequently attack polio vaccination workers in Pakistan, accusing them of being Western spies or part of a plot to sterilize Muslims.
The disease is highly infectious and can cause irreversible paralysis.
The Global Eradication Initiative says polio remains endemic in three countries - Afghanistan, Nigeria and Pakistan. The initiative says until poliovirus transmission is interrupted in these countries, all countries remain at risk of importation of polio.