WASHINGTON: Air travelers from 14 countries will face full-body pat downs before boarding airliners under new security screening procedures targeting foreign passengers announced by the United States on Sunday.

The procedures, which went into effect yesterday, follow the botched Christmas Day bombing attempt on a Detroit-bound US airliner blamed on a Nigerian man who US officials believe was trained by Al-Qaida in Yemen.

Passengers traveling from or through nations listed as "state sponsors of terrorism" - Cuba, Iran, Sudan and Syria - as well as Afghanistan, Algeria, Iraq, Lebanon, Libya, Nigeria, Pakistan, Saudi Arabia, Somalia and Yemen, will face heightened screening, an Obama administration official said.